Method and system for frequency up-conversion

ABSTRACT

A method and system is described wherein a signal with a lower frequency is up-converted to a higher frequency. In one embodiment, the higher frequency signal is used as a stable frequency and phase reference. In another embodiment, the invention is used as a transmitter. The up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency. When the invention is being used as a frequency or phase reference, the oscillating signal is not modulated, and controls a switch that is connected to a bias signal. When the invention is being used in the frequency modulation (FM) or phase modulation (PM) implementations, the oscillating signal is modulated by an information signal before it causes the switch to gate the bias signal. In the amplitude modulation implementation (AM), the oscillating signal is not modulated, but rather causes the switch to gate a reference signal that is substantially equal to or proportional to the information signal. In the FM and PM implementations, the signal that is output from the switch is modulated substantially the same as the modulated oscillating signal. In the AM implementation, the signal that is output from the switch has an amplitude that is a function of the information signal. In both embodiments, the output of the switch is filtered, and the desired harmonic is output.

CROSS-REFERENCE TO OTHER APPLICATIONS

[0001] The following applications of common assignee are related to thepresent application, have the same filing date as the presentapplication, and are herein incorporated by reference in theirentireties:

[0002] “Method and System for Down-Converting Electromagnetic Signals,”Attorney Docket No. 1744.0010000.

[0003] “Method and System for Ensuring Reception of a CommunicationsSignal,” Attorney Docket No. 1744.0030000.

[0004] “Integrated Frequency Translation And Selectivity,” AttorneyDocket No. 1744.0130000.

[0005] “Universal Frequency Translation, and Applications of Same,”Attorney Docket No. 1744.0140000.

BACKGROUND OF THE INVENTION

[0006] 1. Field of the Invention

[0007] The present invention is generally directed to frequencyup-conversion of electromagnetic (EM) signals.

[0008] 2. Related Art

[0009] Modern day communication systems employ components such astransmitters and receivers to transmit information from a source to adestination. To accomplish this transmission, information is imparted ona carrier signal and the carrier signal is then transmitted. Typically,the carrier signal is at a frequency higher than the baseband frequencyof the information signal. Typical ways that the information is impartedon the carrier signal are called modulation.

[0010] Three widely used modulation schemes include: frequencymodulation (FM), where the frequency of the carrier wave changes toreflect the information that has been modulated on the signal; phasemodulation (PM), where the phase of the carrier signal changes toreflect the information imparted on it; and amplitude modulation (AM),where the amplitude of the carrier signal changes to reflect theinformation. Also, these modulation schemes are used in combination witheach other (e.g., AM combined with FM and AM combined with PM).

SUMMARY OF THE INVENTION

[0011] The present invention is directed to methods and systems toup-convert a signal from a lower frequency to a higher frequency, andapplications thereof.

[0012] In one embodiment, the invention uses a stable, low frequencysignal to generate a higher frequency signal with a frequency and phasethat can be used as stable references.

[0013] In another embodiment, the present invention is used as atransmitter. In this embodiment, the invention accepts an informationsignal at a baseband frequency and transmits a modulated signal at afrequency higher than the baseband frequency.

[0014] The methods and systems of transmitting vary slightly dependingon the modulation scheme being used. For some embodiments usingfrequency modulation (FM) or phase modulation (PM), the informationsignal is used to modulate an oscillating signal to create a modulatedintermediate signal. If needed, this modulated intermediate signal is“shaped” to provide a substantially optimum pulse-width-to-period ratio.This shaped signal is then used to control a switch which opens andcloses as a function of the frequency and pulse width of the shapedsignal. As a result of this opening and closing, a signal that isharmonically rich is produced with each harmonic of the harmonicallyrich signal being modulated substantially the same as the modulatedintermediate signal. Through proper filtering, the desired harmonic (orharmonics) is selected and transmitted.

[0015] For some embodiments using amplitude modulation (AM), the switchis controlled by an unmodulated oscillating signal (which may, ifneeded, be shaped). As the switch opens and closes, it gates a referencesignal which is the information signal. In an alternate implementation,the information signal is combined with a bias signal to create thereference signal, which is then gated. The result of the gating is aharmonically rich signal having a fundamental frequency substantiallyproportional to the oscillating signal and an amplitude substantiallyproportional to the amplitude of the reference signal. Each of theharmonics of the harmonically rich signal also have amplitudesproportional to the reference signal, and are thus considered to beamplitude modulated. Just as with the FM/PM embodiments described above,through proper filtering, the desired harmonic (or harmonics) isselected and transmitted.

[0016] Further features and advantages of the invention, as well as thestructure and operation of various embodiments of the invention, aredescribed in detail below with reference to the accompanying figures.The left-most digit(s) of a reference number typically identifies thefigure in which the reference number first appears.

BRIEF DESCRIPTION OF THE FIGURES

[0017]FIG. 1 illustrates a circuit for a frequency modulation (FM)transmitter;

[0018]FIGS. 2A, 2B, and 2C illustrate typical waveforms associated withthe FIG. 1 FM circuit for a digital information signal;

[0019]FIG. 3 illustrates a circuit for a phase modulation (PM)transmitter;

[0020]FIGS. 4A, 4B, and 4C illustrate typical waveforms associated withthe FIG. 3 PM circuit for a digital information signal;

[0021]FIG. 5 illustrates a circuit for an amplitude modulation (AM)transmitter;

[0022]FIGS. 6A, 6B, and 6C illustrate typical waveforms associated withthe FIG. 5 AM circuit for a digital information signal;

[0023]FIG. 7 illustrates a circuit for an in-phase/quadrature-phasemodulation (“I/Q”) transmitter;

[0024]FIGS. 8A, 8B, 8C, 8D, and 8E illustrate typical waveformsassociated with the FIG. 7 “I/Q” circuit for digital information signal;

[0025]FIG. 9 illustrates the high level operational flowchart of atransmitter according to an embodiment of the present invention;

[0026]FIG. 10 illustrates the high level structural block diagram of thetransmitter of an embodiment of the present invention;

[0027]FIG. 11 illustrates the operational flowchart of a firstembodiment (i.e., FM mode) of the present invention;

[0028]FIG. 12 illustrates an exemplary structural block diagram of thefirst embodiment (i.e., FM mode) of the present invention;

[0029]FIG. 13 illustrates the operational flowchart of a secondembodiment (i.e., PM mode) of the present invention;

[0030]FIG. 14 illustrates an exemplary structural block diagram of thesecond embodiment (i.e., PM mode) of the present invention;

[0031]FIG. 15 illustrates the operational flowchart of a thirdembodiment (i.e., AM mode) of the present invention;

[0032]FIG. 16 illustrates an exemplary structural block diagram of thethird embodiment (i.e., AM mode) of the present invention;

[0033]FIG. 17 illustrates the operational flowchart of a fourthembodiment (i.e., “I/Q” mode) of the present invention;

[0034]FIG. 18 illustrates an exemplary structural block diagram of thefourth embodiment (i.e., “I/Q” mode) of the present invention;

[0035] FIGS. 19A-19I illustrate exemplary waveforms (for a frequencymodulation mode operating in a frequency shift keying embodiment) at aplurality of points in an exemplary high level circuit diagram;

[0036]FIGS. 20A, 20B, 20C illustrate typical waveforms associated withthe FIG. 1 FM circuit for an analog information signal;

[0037]FIGS. 21A, 21B, 21C illustrate typical waveforms associated withthe FIG. 3 PM circuit for an analog information signal;

[0038]FIGS. 22A, 22B, 22C illustrate typical waveforms associated withthe FIG. 5 AM circuit for an analog information signal;

[0039]FIG. 23 illustrates an implementation example of a voltagecontrolled oscillator (VCO);

[0040]FIG. 24 illustrates an implementation example of a localoscillator (LO);

[0041]FIG. 25 illustrates an implementation example of a phase shifter;

[0042]FIG. 26 illustrates an implementation example of a phasemodulator;

[0043]FIG. 27 illustrates an implementation example of a summingamplifier;

[0044] FIGS. 28A-28C illustrate an implementation example of a switchmodule for the FM and PM modes;

[0045] FIGS. 29A-29C illustrate an example of the switch module of FIGS.28A-28C wherein the switch is a GaAsFET;

[0046] FIGS. 30A-30C illustrate an example of a design to ensuresymmetry for a GaAsFET implementation in the FM and PM modes;

[0047] FIGS. 31A-31C illustrate an implementation example of a switchmodule for the AM mode;

[0048] FIGS. 32A-31C illustrate the switch module of FIGS. 31A-31Cwherein the switch is a GaAsFET;

[0049] FIGS. 33A-33C illustrates an example of a design to ensuresymmetry for a GaAsFET implementation in the AM mode;

[0050]FIG. 34 illustrates an implementation example of a summer;

[0051]FIG. 35 illustrates an implementation example of a filter;

[0052]FIG. 36 is a representative spectrum demonstrating the calculationof “Q;”

[0053]FIGS. 37A and 37B are representative examples of filter circuits;

[0054]FIG. 38 illustrates an implementation example of a transmissionmodule;

[0055]FIG. 39A shows a first exemplary pulse shaping circuit usingdigital logic devices for a squarewave input from an oscillator;

[0056]FIGS. 39B, 39C, and 39D illustrate waveforms associated with theFIG. 39A circuit;

[0057]FIG. 40A shows a second exemplary pulse shaping circuit usingdigital logic devices for a squarewave input from an oscillator;

[0058]FIGS. 40B, 40C, and 40D illustrate waveforms associated with theFIG. 40A circuit;

[0059]FIG. 41 shows a third exemplary pulse shaping circuit for anyinput from an oscillator;

[0060]FIGS. 42A, 42B, 42C, 42D, and 42E illustrate representativewaveforms associated with the FIG. 41 circuit;

[0061]FIG. 43 shows the internal circuitry for elements of FIG. 41according to an embodiment of the invention;

[0062] FIGS. 44A-44G illustrate exemplary waveforms (for a pulsemodulation mode operating in a pulse shift keying embodiment) at aplurality of points in an exemplary high level circuit diagram,highlighting the characteristics of the first three harmonics;

[0063] FIGS. 45A-45F illustrate exemplary waveforms (for an amplitudemodulation mode operating in an amplitude shift keying embodiment) at aplurality of points in an exemplary high level circuit diagram,highlighting the characteristics of the first three harmonics;

[0064]FIG. 46 illustrates an implementation example of a harmonicenhancement module;

[0065]FIG. 47 illustrates an implementation example of an amplifiermodule;

[0066]FIGS. 48A and 48B illustrate exemplary circuits for a linearamplifier;

[0067]FIG. 49 illustrates a typical superheterodyne receiver;

[0068]FIG. 50 illustrates a transmitter according to an embodiment ofthe present invention in a transceiver circuit with a typicalsuperheterodyne receiver in a full-duplex mode;

[0069]FIGS. 51A, 51B, 51C, and 51D illustrate a transmitter according toan embodiment of the present invention in a transceiver circuit using acommon oscillator with a typical superheterodyne receiver in ahalf-duplex mode;

[0070]FIG. 52 illustrates an exemplary receiver using universalfrequency down conversion techniques according to an embodiment;

[0071]FIG. 53 illustrates an exemplary transmitter of the presentinvention;

[0072]FIGS. 54A, 54B, and 54C illustrate an exemplary transmitter of thepresent invention in a transceiver circuit with a universal frequencydown conversion receiver operating in a half-duplex mode for the FM andPM modulation embodiment;

[0073]FIG. 55 illustrates an exemplary transmitter of the presentinvention in a transceiver circuit with a universal frequency downconversion receiver operating in a half-duplex mode for the AMmodulation embodiment;

[0074]FIG. 56 illustrates an exemplary transmitter of the presentinvention in a transceiver circuit with a universal frequency downconversion receiver operating in a full-duplex mode;

[0075] FIGS. 57A-57C illustrate an exemplary transmitter of the presentinvention being used in frequency modulation, phase modulation, andamplitude modulation embodiments, including a pulse shaping circuit andan amplifier module;

[0076]FIG. 58 illustrates harmonic amplitudes for apulse-width-to-period ratio of 0.01;

[0077]FIG. 59 illustrates harmonic amplitudes for apulse-width-to-period ratio of 0.0556;

[0078]FIG. 60 is a table that illustrates the relative amplitudes of thefirst 50 harmonics for six exemplary pulse-width-to-period ratios;

[0079]FIG. 61 is a table that illustrates the relative amplitudes of thefirst 25 harmonics for six pulse-width-to-period ratios optimized forthe 1^(st) through 10^(th) subharmonics;

[0080]FIG. 62 illustrates an exemplary structural block diagram for analternative embodiment of the present invention (i.e., a mode wherein AMis combined with PM);

[0081] FIGS. 63A-63H illustrate exemplary waveforms (for the embodimentof FIG. 62) at a plurality of points in an exemplary high level circuitdiagram, highlighting the characteristics of the first two harmonics;

[0082] FIGS. 64A and 64A1 illustrate exemplary implementations ofaliasing modules; and

[0083] FIGS. 64B-64F illustrate exemplary waveforms at a plurality ofpoints in the FIGS. 64A and 64A1 circuits.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0084] Table of Contents

[0085] 1. Terminology.

[0086] 2. Overview of the Invention.

[0087] 2.1 Discussion of Modulation Techniques.

[0088] 2.2 Explanation of Exemplary Circuits and Waveforms.

[0089] 2.2.1 Frequency Modulation.

[0090] 2.2.2 Phase Modulation.

[0091] 2.2.3 Amplitude Modulation.

[0092] 2.2.4 In-phase/Quadrature-phase Modulation.

[0093] 2.3 Features of the Invention.

[0094] 3. Frequency Up-conversion.

[0095] 3.1 High Level Description.

[0096] 3.1.1 Operational Description.

[0097] 3.1.2 Structural Description.

[0098] 3.2 Exemplary Embodiments.

[0099] 3.2.1 First Embodiment: Frequency Modulation (FM) Mode.

[0100] 3.2.1.1 Operational Description.

[0101] 3.2.1.2 Structural Description.

[0102] 3.2.2 Second Embodiment: Phase Modulation (PM) Mode.

[0103] 3.2.2.1 Operational Description.

[0104] 3.2.2.2 Structural Description.

[0105] 3.2.3 Third Embodiment: Amplitude Modulation (AM) Mode.

[0106] 3.2.3.1 Operational Description.

[0107] 3.2.3.2 Structural Description.

[0108] 3.2.4 Fourth Embodiment: In-phase/Quadrature-phase (“I/Q”)Modulation Mode.

[0109] 3.2.4.1 Operational Description.

[0110] 3.2.4.2 Structural Description.

[0111] 3.2.5 Other Embodiments.

[0112] 3.3 Methods and Systems for Implementing the Embodiments.

[0113] 3.3.1 The Voltage Controlled Oscillator (FM Mode).

[0114] 3.3.1.1 Operational Description.

[0115] 3.3.1.2 Structural Description.

[0116] 3.3.2 The Local Oscillator (PM, AM, and “I/Q” Modes).

[0117] 3.3.2.1 Operational Description.

[0118] 3.3.2.2 Structural Description.

[0119] 3.3.3 The Phase Shifter (PM Mode).

[0120] 3.3.3.1 Operational Description.

[0121] 3.3.3.2 Structural Description.

[0122] 3.3.4 The Phase Modulator (PM and “I/Q” Modes).

[0123] 3.3.4.1 Operational Description;

[0124] 3.3.4.2 Structural Description.

[0125] 3.3.5 The Summing Module (AM Mode).

[0126] 3.3.5.1 Operational Description.

[0127] 3.3.5.2 Structural Description.

[0128] 3.3.6 The Switch Module (FM, PM, and “I/Q” Modes).

[0129] 3.3.6.1 Operational Description.

[0130] 3.3.6.2 Structural Description.

[0131] 3.3.7 The Switch Module (AM Mode).

[0132] 3.3.7.1 Operational Description.

[0133] 3.3.7.2 Structural Description.

[0134] 3.3.8 The Summer (“I/Q” Mode).

[0135] 3.3.8.1 Operational Description.

[0136] 3.3.8.2 Structural Description.

[0137] 3.3.9 The Filter (FM, PM, AM, and “I/Q” Modes).

[0138] 3.3.9.1 Operational Description.

[0139] 3.3.9.2 Structural Description.

[0140] 3.3.10 The Transmission Module (FM, PM, AM, and “I/Q” Modes).

[0141] 3.3.10.1 Operational Description.

[0142] 3.3.10.2 Structural Description.

[0143] 3.3.11 Other Implementations.

[0144] 4. Harmonic Enhancement.

[0145] 4.1 High Level Description.

[0146] 4.1.1 Operational Description.

[0147] 4.1.2 Structural Description.

[0148] 4.2 Exemplary Embodiments.

[0149] 4.2.1 First Embodiment: When a Square Wave Feeds the HarmonicEnhancement Module to Create One Pulse per Cycle.

[0150] 4.2.1.1 Operational Description.

[0151] 4.2.1.2 Structural Description.

[0152] 4.2.2 Second Embodiment: When a Square Wave Feeds the HarmonicEnhancement Module to Create Two Pulses per Cycle.

[0153] 4.2.2.1 Operational Description.

[0154] 4.2.2.2 Structural Description.

[0155] 4.2.3 Third Embodiment: When Any Waveform Feeds the HarmonicEnhancement Module.

[0156] 4.2.3.1 Operational Description.

[0157] 4.2.3.2 Structural Description.

[0158] 4.2.4 Other Embodiments.

[0159] 4.3 Implementation Examples.

[0160] 4.3.1 First Digital Logic Circuit.

[0161] 4.3.2 Second Digital Logic Circuit.

[0162] 4.3.3 Analog Circuit.

[0163] 4.3.4 Other Implementations.

[0164] 5. Amplifier Module.

[0165] 5.1 High Level Description.

[0166] 5.1.1 Operational Description.

[0167] 5.1.2 Structural Description.

[0168] 5.2 Exemplary Embodiment.

[0169] 5.2.1 Linear Amplifier.

[0170] 5.2.1.1 Operational Description.

[0171] 5.2.1.2 Structural Description.

[0172] 5.2.2 Other Embodiments.

[0173] 5.3 Implementation Examples.

[0174] 5.3.1 Linear Amplifier.

[0175] 5.3.1.1 Operational Description.

[0176] 5.3.1.2 Structural Description.

[0177] 5.3.2 Other Implementations.

[0178] 6. Receiver/Transmitter System.

[0179] 6.1 High Level Description.

[0180] 6.2 Exemplary Embodiments and Implementation Examples.

[0181] 6.2.1 First Embodiment: The Transmitter of the Present InventionBeing Used in a Circuit with a Superheterodyne Receiver.

[0182] 6.2.2 Second Embodiment: The Transmitter of the Present InventionBeing Used with a Universal Frequency Down Converter in a Half-DuplexMode.

[0183] 6.2.3 Third Embodiment: The Transmitter of the Present InventionBeing Used with a Universal Frequency Down Converter in a Full-DuplexMode.

[0184] 6.2.4 Other Embodiments and Implementations.

[0185] 6.3 Summary Description of Down-conversion Using a UniversalFrequency Translation Module.

[0186] 7. Designing a Transmitter According to an Embodiment of thePresent Invention.

[0187] 7.1 Frequency of the Transmission Signal.

[0188] 7.2 Characteristics of the Transmission Signal.

[0189] 7.3 Modulation Scheme.

[0190] 7.4 Characteristics of the Information Signal.

[0191] 7.5 Characteristic of the Oscillating Signal.

[0192] 7.5.1 Frequency of the Oscillating Signal.

[0193] 7.5.2 Pulse Width of the String of Pulses.

[0194] 7.6 Design of the Pulse Shaping Circuit.

[0195] 7.7 Selection of the Switch.

[0196] 7.8 Design of the Filter.

[0197] 7.9 Selection of an Amplifier.

[0198] 7.10 Design of the Transmission Module.

[0199] 1. Terminology.

[0200] Various terms used in this application are generally described inthis section. Each description in this section is provided forillustrative and convenience purposes only, and is not limiting. Themeaning of these terms will be apparent to persons skilled in therelevant art(s) based on the entirety of the teachings provided herein.

[0201] Amplitude Modulation (AM): A modulation technique wherein theamplitude of the carrier signal is shifted (i.e., varied) as a functionof the information signal. The frequency of the carrier signal typicallyremains constant. A subset of AM is referred to as “amplitude shiftkeying” which is used primarily for digital communications where theamplitude of the carrier signal shifts between discrete states ratherthan varying continuously as it does for analog information.

[0202] Analog signal: A signal in which the information containedtherein is continuous as contrasted to discrete, and represents a timevarying physical event or quantity. The information content is conveyedby varying at least one characteristic of the signal, such as but notlimited to amplitude, frequency, or phase, or any combinations thereof.

[0203] Baseband signal: Any generic information signal desired fortransmission and/or reception. As used herein, it refers to both theinformation signal that is generated at a source prior to anytransmission (also referred to as the modulating baseband signal), andto the signal that is to be used by the recipient after transmission(also referred to as the demodulated baseband signal).

[0204] Carrier signal: A signal capable of carrying information.Typically, it is an electromagnetic signal that can be varied through aprocess called modulation. The frequency of the carrier signal isreferred to as the carrier frequency. A communications system may havemultiple carrier signals at different carrier frequencies.

[0205] Control a switch: Causing a switch to open and close. The switchmay be, without limitation, mechanical, electrical, electronic, optical,etc., or any combination thereof. Typically, it is controlled by anelectrical or electronic input. If the switch is controlled by anelectronic signal, it is typically a different signal than the signalsconnected to either terminal of the switch.

[0206] Demodulated baseband signal: The baseband signal that is to beused by the recipient after transmission. Typically it has been downconverted from a carrier signal and has been demodulated. Thedemodulated baseband signal should closely approximate the informationsignal (i.e., the modulating baseband signal) in frequency, amplitude,and information.

[0207] Demodulation: The process of removing information from a carrieror intermediate frequency signal.

[0208] Digital signal: A signal in which the information containedtherein has discrete states as contrasted to a signal that has aproperty that may be continuously variable.

[0209] Direct down conversion: A down conversion technique wherein areceived signal is directly down converted and demodulated, ifapplicable, from the original transmitted frequency (i.e., a carrierfrequency) to baseband without having an intermediate frequency.

[0210] Down conversion: A process for performing frequency translationin which the final frequency is lower than the initial frequency.

[0211] Drive a switch: Same as control a switch.

[0212] Frequency Modulation (FM): A modulation technique wherein thefrequency of the carrier signal is shifted (i.e., varied) as a functionof the information signal. A subset of FM is referred to as “frequencyshift keying” which is used primarily for digital communications wherethe frequency of the carrier signal shifts between discrete statesrather than varying continuously as it does for analog information.

[0213] Harmonic: A harmonic is a frequency or tone that, when comparedto its fundamental or reference frequency or tone, is an integermultiple of it. In other words, if a periodic waveform has a fundamentalfrequency of “f” (also called the first harmonic), then its harmonicsmay be located at frequencies of “n·f,” where “n” is 2, 3, 4, etc. Theharmonic corresponding to n=2 is referred to as the second harmonic, theharmonic corresponding to n=3 is referred to as the third harmonic, andso on.

[0214] In-phase (“I”) signal: The signal typically generated by anoscillator. It has not had its phase shifted and is often represented asa sine wave to distinguish it from a “Q” signal. The “I” signal can,itself, be modulated by any means. When the “I” signal is combined witha “Q” signal, the resultant signal is referred to as an “I/Q” signal.

[0215] In-phase/Quadrature-phase (“I/Q”) signal: The signal that resultswhen an “I” signal is summed with a “Q” signal. Typically, both the “I”and “Q” signals have been phase modulated, although other modulationtechniques may also be used, such as amplitude modulation. An “I/Q”signal is used to transmit separate streams of informationsimultaneously on a single transmitted carrier. Note that the modulated“I” signal and the modulated “Q” signal are both carrier signals havingthe same frequency. When combined, the resultant “I/Q” signal is also acarrier signal at the same frequency.

[0216] Information signal: The signal that contains the information thatis to be transmitted. As used herein, it refers to the original basebandsignal at the source. When it is intended that the information signalmodulate a carrier signal, it is also referred to as the “modulatingbaseband signal.” It may be voice or data, analog or digital, or anyother signal or combination thereof.

[0217] Intermediate frequency (IF) signal: A signal that is at afrequency between the frequency of the baseband signal and the frequencyof the transmitted signal.

[0218] Modulation: The process of varying one or more physicalcharacteristics of a signal to represent the information to betransmitted. Three commonly used modulation techniques are frequencymodulation, phase modulation, and amplitude modulation. There are alsovariations, subsets, and combinations of these three techniques.

[0219] Operate a switch: Same as control a switch.

[0220] Phase Modulation (PM): A modulation technique wherein the phaseof the carrier signal is shifted (i.e., varied) as a function of theinformation signal. A. subset of PM is referred to as “phase shiftkeying” which is used primarily for digital communications where thephase of the carrier signal shifts between discrete states rather thanvarying continuously as it does for analog information.

[0221] Quadrature-phase (“Q”) signal: A signal that is out of phase withan in-phase (“I”) signal. The amount of phase shift is predetermined fora particular application, but in a typical implementation, the “Q”signal is 90° out of phase with the “I” signal. Thus, if the “I” signalwere a sine wave, the “Q” signal would be a cosine wave. When discussedtogether, the “I” signal and the “Q” signal have the same frequencies.

[0222] Spectrum: Spectrum is used to signify a continuous range offrequencies, usually wide, within which electromagnetic (EM) waves havesome specific common characteristic. Such waves may be propagated in anycommunication medium, both natural and manmade, including but notlimited to air, space, wire, cable, liquid, waveguide, microstrip,stripline, optical fiber, etc. The EM spectrum includes all frequenciesgreater than zero hertz.

[0223] Subharmonic: A subharmonic is a frequency or tone that is aninteger submultiple of a referenced fundamental frequency or tone. Thatis, a subharmonic frequency is the quotient obtained by dividing thefundamental frequency by an integer. For example, if a periodic waveformhas a frequency of “f” (also called the “fundamental frequency” or firstsubharmonic), then its subharmonics have frequencies of “f/n,” where nis 2, 3, 4, etc. The subharmonic corresponding to n=2 is referred to asthe second subharmonic, the subharmonic corresponding to n=3 is referredto as the third subharmonic, and so on. A subharmonic itself haspossible harmonics, and the i^(th) harmonic of the i^(th) subharmonicwill be at the fundamental frequency of the original periodic waveform.For example, the third subharmonic (which has a frequency of “f/3”) mayhave harmonics at integer multiples of itself (i.e., a second harmonicat “2·f/3,” a third harmonic at “3·f/3,” and so on). The third harmonicof the third subharmonic of the original signal (i.e., “3·f/3”) is atthe frequency of the original signal.

[0224] Trigger a switch: Same as control a switch.

[0225] Up conversion: A process for performing frequency translation inwhich the final frequency is higher than the initial frequency.

[0226] 2. Overview of the Invention.

[0227] The present invention is directed to systems and methods forfrequency up-conversion, and applications thereof.

[0228] In one embodiment, the frequency up-converter of the presentinvention is used as a stable reference frequency source in a phasecomparator or in a frequency comparator. This embodiment of the presentinvention achieves this through the use of a stable, low frequency localoscillator, a switch, and a filter. Because it up-converts frequency,the present invention can take advantage of the relatively low cost oflow frequency oscillators to generate stable, high frequency signals.

[0229] In a second embodiment, the frequency up-converter is used as asystem and method for transmitting an electromagnetic (EM) signal.

[0230] Based on the discussion contained herein, one skilled in therelevant art(s) will recognize that there are other, alternativeembodiments in which the frequency up-converter of the present inventioncould be used in other applications, and that these alternativeembodiments fall within the scope of the present invention.

[0231] For illustrative purposes, various modulation examples arediscussed below. However, it should be understood that the invention isnot limited by these examples. Other modulation techniques that might beused with the present invention will be apparent to persons skilled inthe relevant art(s) based on the teaching contained herein.

[0232] Also for illustrative purposes, frequency up-conversion accordingto the present invention is described below in the context of atransmitter. However, the invention is not limited to this embodiment.Equivalents, extensions, variations, deviations, etc., of the followingwill be apparent to persons skilled in the relevant art(s) based on theteachings contained herein. Such equivalents, extensions, variations,deviations, etc., are within the scope and spirit of the presentinvention.

[0233] 2.1 Discussion of Modulation Techniques.

[0234] Techniques by which information can be imparted onto EM signalsto be transmitted are called modulation. These techniques are generallywell known to one skilled in the relevant art(s), and include, but arenot limited to, frequency modulation (FM), phase modulation (PM),amplitude modulation (AM), quadrature-phase shift keying (QPSK),frequency shift keying (FSK), phase shift keying (PSK), amplitude shiftkeying (ASK), etc., and combinations thereof. These last threemodulation techniques, FSK, PSK, and ASK, are subsets of FM, PM, and AM,respectively, and refer to circuits having discrete input signals (e.g.,digital input signals).

[0235] For illustrative purposes only, the circuits and techniquesdescribed below all refer to the EM broadcast medium. However, theinvention is not limited by this embodiment. Persons skilled in therelevant art(s) will recognize that these same circuits and techniquescan be used in all transmission media (e.g., over-the-air broadcast,point-to-point cable, etc.).

[0236] 2.2 Explanation of Exemplary Circuits and Waveforms.

[0237] 2.2.1 Frequency Modulation.

[0238]FIG. 1 illustrates an example of a frequency modulation (FM)circuit 100 and FIGS. 2A, 2B, and 2C, and FIGS. 20A, 20B, and 20Cillustrate examples of waveforms at several points in FM circuit 100. Inan FM system, the frequency of a carrier signal, such as an oscillatingsignal 202 (FIG. 2B and FIG. 20B), is varied to represent the data to becommunicated, such as information signals 102 of FIGS. 2A and 2002 ofFIG. 20A. In FIG. 20A, information signal 2002 is a continuous signal(i.e., an analog signal), and in FIG. 2A, information signal 102 is adiscrete signal (i.e., a digital signal). In the case of the discreteinformation signal 102, the FM circuit 100 is referred to as a frequencyshift keying (FSK) system, which is a subset of an FM system.

[0239] Frequency modulation circuit 100 receives, an information signal102, 2002 from a source (not shown). Information signal 102, 2002 can beamplified by an optional amplifier 104 and filtered by an optionalfilter 114 and is the voltage input that drives a voltage controlledoscillator (VCO) 106. Within VCO 106, an oscillating signal 202 (seen onFIG. 2B and FIG. 20B) is generated. The purpose of VCO 106 is to varythe frequency of oscillating signal 202 as a function of the inputvoltage, i.e., information signal 102, 2002. The output of VCO 106 is amodulated signal shown as modulated signal 108 (FIG. 2C) when theinformation signal is the digital information signal 102 and shown asmodulated signal 2004 (FIG. 20C) when the information signal is theanalog signal 2002. Modulated signal 108, 2004 is at a relatively lowfrequency (e.g., generally between 50 MHz and 100 MHz) and can have itsfrequency increased by an optional frequency multiplier 110 (e.g., to900 MHz, 1.8 GHz) and have its amplitude increased by an optionalamplifier 116. The output of optional frequency multiplier 110 and/oroptional amplifier 116 is then transmitted by an exemplary antenna 112.

[0240] 2.2.2 Phase Modulation.

[0241]FIG. 3 illustrates an example of a phase modulation (PM) circuit300 and FIGS. 4A, 4B, and 4C, and FIGS. 21A, 21B, and 21C illustrateexamples of waveforms at several points in PM circuit 300. In a PMsystem, the phase of a carrier signal, such as a local oscillator (LO)output 308 (FIG. 4B and FIG. 21B), is varied to represent the data to becommunicated, such as an information signals 302 of FIGS. 4A and 2102 ofFIG. 21A. In FIG. 21A, information signal 2102 is a continuous signal(i.e., an analog signal), and in FIG. 4A, information signal 302 is adiscrete signal (i.e., a digital signal). In the case of the discreteinformation signal 302, the PM circuit is referred to as a phase shiftkeying (PSK) system. This is the typical implementation, and is a subsetof a PM system.

[0242] Phase modulation circuit 300 receives information signal 302,2102 from a source (not shown). Information signal 302, 2102 can beamplified by an optional amplifier 304 and filtered by an optionalfilter 318 and is routed to a phase modulator 306. Also feeding phasemodulator 306 is LO output 308 of a local oscillator 310. LO output 308is shown on FIG. 4B and FIG. 21B. Local oscillators, such as localoscillator 310, output an electromagnetic wave at a predeterminedfrequency and amplitude.

[0243] The output of phase modulator 306 is a modulated signal shown asa phase modulated signal 312 (FIG. 4C) when the information signal isthe discrete information signal 302 and shown as a phase modulatedsignal 2104 (FIG. 21C) when the information signal is the analoginformation signal 2102. The purpose of phase modulator 306 is to changethe phase of LO output 308 as a function of the value of informationsignal 302, 2102. That is, for example in a PSK mode, if LO output 308were a sine wave, and the value of information signal 302 changed from abinary high to a binary low, the phase of LO output 308 would changefrom a sine wave with a zero phase to a sine wave with, for example, aphase of 180°. The result of this phase change would be phase modulatedsignal 312 of FIG. 4C which would have the same frequency as LO output308, but would be out of phase by 180° in this example. For a PSKsystem, the phase changes in phase modulated signal 312 that arerepresentative of the information in information signal 302 can be seenby comparing waveforms 302, 308, and 312 on FIGS. 4A, 4B, and 4C. Forthe case of an analog information signal 2102 of FIG. 21A, the phase ofLO output 308 of FIG. 21B changes continuously as a function of theamplitude of the information signal 2102. That is, for example, asinformation signal 2102 increases from a value of “X” to “X+δx”, the PMsignal 2104 of FIG. 21C changes from a signal which may be representedby the equation sin (ωt) to a signal which can be represented by theequation sin (ωt+4)), where φ is the phase change associated with achange of δx in information signal 2102. For an analog PM system, thephase changes in phase modulated signal 2104 that are representative ofthe information in information signal 2102 can be seen by comparingwaveforms 2102, 308, and 2104 on FIGS. 21A, 21B, and 21C.

[0244] After information signal 302, 2102 and LO output 308 have beenmodulated by phase modulator 306, phase modulated signal 312, 2104 canbe routed to an optional frequency multiplier 314 and optional amplifier320. The purpose of optional frequency multiplier 314 is to increase thefrequency of phase modulated signal 312 from a relatively low frequency(e.g., 50 MHz to 100 MHz) to a desired broadcast frequency (e.g., 900MHz, 1.8 GHz). Optional amplifier 320 raises the signal strength ofphase modulated signal 312, 2104 to a desired level to be transmitted byan exemplary antenna 316.

[0245] 2.2.3 Amplitude Modulation.

[0246]FIG. 5 illustrates an example of an amplitude modulation (AM)circuit 500 and FIGS. 6A, 6B, and 6C, and FIGS. 22A, 22B, and 22Cillustrate examples of waveforms at several points in AM circuit 500. Inan AM system, the amplitude of a carrier signal, such as a localoscillator (LO) signal 508 (FIG. 6B and FIG. 22B), is varied torepresent the data to be communicated, such as information signals 502of FIGS. 6A and 2202 of FIG. 22A. In FIG. 22A, information signal 2202is a continuous signal (i.e., an analog signal), and in FIG. 6A,information signal 502 is a discrete signal (i.e., a digital signal). Inthe case of the discrete information signal 502, the AM circuit isreferred to as an amplitude shift keying (ASK) system, which is a subsetof an AM system.

[0247] Amplitude modulation circuit 500 receives information signal 502from a source (not shown). Information signal 502, 2202 can be amplifiedby an optional amplifier 504 and filtered by an optional filter 518.Amplitude modulation circuit 500 also includes a local oscillator (LO)506 which has an LO output 508. Information signal 502, 2202 and LOoutput 508 are then multiplied by a multiplier 510. The purpose ofmultiplier 510 is to cause the amplitude of LO output 508 to vary as afunction of the amplitude of information signal 502, 2202. The output ofmultiplier 510 is a modulated signal shown as amplitude modulated signal512 (FIG. 6C) when the information signal is the digital informationsignal 502 and shown as modulated signal 2204 (FIG. 22C) when theinformation signal is the analog information signal 2202. AM signal 512,2204 can then be routed to an optional frequency multiplier 514 wherethe frequency of AM signal 512, 2204 is increased from a relatively lowlevel (e.g., 50 MHz to 100 MHz) to a higher level desired for broadcast(e.g., 900 MHz, 1.8 GHz) and an optional amplifier 520, which increasesthe signal strength of AM signal 512, 2204 to a desired level forbroadcast by an exemplary antenna 516.

[0248] 2.2.4 In-Phase/Quadrature-Phase Modulation.

[0249]FIG. 7 illustrates an example of an in-phase/quadrature-phase(“I/Q”) modulation circuit 700 and FIGS. 8A, 8B, 8C, 8D, and 8Eillustrate examples of waveforms at several points in “I/Q” modulationcircuit 700. In this technique, which increases bandwidth efficiency,separate information signals can be simultaneously transmitted oncarrier signals that are out of phase with each other. That is, a firstinformation signal 702 of FIG. 8A can be modulated onto the in-phase(“I”) oscillator signal 710 of FIG. 8B and a second information signal704 of FIG. 8C can be modulated onto the quadrature-phase (“Q”)oscillator signal 712 of FIG. 8D. The “I” modulated signal is combinedwith the “Q” modulated signal and the resulting “I/Q” modulated signalis then transmitted. In a typical usage, both information signals aredigital, and both are phase modulated onto the “I” and “Q” oscillatingsignals. One skilled in the relevant art(s) will recognize that the“I/Q” mode can also work with analog information signals, withcombinations of analog and digital signals, with other modulationtechniques, or any combinations thereof.

[0250] This “I/Q” modulation system uses two PM circuits together inorder to increase the bandwidth efficiency. As stated above, in a PMcircuit, the phase of an oscillating signal, such as 710 (or 712) (FIGS.8B or 8D), is varied to represent the data to be communicated, such asan information signal such as 702 (or 704). For ease of understandingand display, the discussion herein will describe the more typical use ofthe “I/Q” mode, that is, with digital information signals and phasemodulation on both oscillating signals. Thus, both signal streams arephase shift keying (PSK), which is a subset of PM.

[0251] “I/Q” modulation circuit 700 receives an information signal 702from a first source (not shown) and an information signal 704 from asecond source (not shown). Examples of information signals 702 and 704are shown in FIGS. 8A and 8C. Information signals 702 and 704 can beamplified by optional amplifiers 714 and 716 and filtered by optionalfilters 734 and 736. It is then routed to phase modulators 718 and 720.Also feeding phase modulators 718 and 720 are oscillating signals 710and 712. Oscillating signal 710 was generated by a local oscillator 706,and is shown in FIG. 8B, and oscillating signal 712 is the phase shiftedoutput of local oscillator 706. Local oscillators, such as localoscillator 706, output an electromagnetic wave at a predeterminedfrequency and amplitude.

[0252] The output of phase modulator 718 is a phase modulated signal 722which is shown using a dotted line as one of the waveforms in FIG. 8E.Similarly, the output of phase modulator 720, which operates in a mannersimilar to phase modulator 718, is a phase modulated signal 724 which isshown using a solid line as the other waveform in FIG. 8E. The effect ofphase modulators 718 and 720 on oscillating signals 710 and 712 is tocause them to change phase. As stated above, the system shown here is aPSK system, and as such, the phase of oscillating signals 710 and 712 isshifted by phase modulators 718 and 720 by a discrete amount as afunction of information signals 702 and 704.

[0253] For simplicity of discussion and ease of display, oscillatingsignal 710 is shown on FIG. 8B as a sine wave and is referred to as the“I” signal in the “I/Q” circuit 700. After the output of oscillator 706has gone through a phase shifter 708, shown here as shifting the phaseby −π/2, oscillating signal 712 is a cosine wave, shown on FIG. 8D, andis referred to as the “Q” signal in the “I/Q” circuit. Again, for easeof display, phase modulators 718 and 720 are shown as shifting the phaseof the respective oscillating signals 710 and 712 by 180°. This is seenon FIG. 8E. Modulated signal 722 is summed with modulated signal 724 bya summer 726. The output of summer 726 is the arithmetic sum ofmodulated signal 722 and 724 and is an “I/Q” signal 728. (For clarity ofthe display on FIG. 8E, the combined signal 728 is not shown. However,one skilled in the relevant art(s) will recognize that the arithmeticsum of 2 sinusoidal waves having the same frequency is also a sinusoidalwave at that frequency.)

[0254] “I/Q” signal 728 can then be routed to an optional frequencymultiplier 730, where the frequency of “I/Q” signal 718 is increasedfrom a relatively low level (e.g., 50 MHz to 100 MHz) to a higher leveldesired for broadcast (e.g., 900 MHz, 1.8 GHz), and to an optionalamplifier 738 which increases the signal strength of “I/Q” signal 728 toa desired level for broadcast by an exemplary antenna 732.

[0255] 2.3 Features of the Invention.

[0256] As apparent from the above, several frequencies are involved in acommunications system. The frequency of the information signal isrelatively low. The frequency of the local oscillator (both the voltagecontrolled oscillator as well as the other oscillators) is higher thanthat of the information signal, but typically not high enough forefficient transmission. A third frequency, not specifically mentionedabove, is the frequency of the transmitted signal which is greater thanor equal to the frequency of the oscillating signal. This is thefrequency that is routed from the optional frequency multipliers andoptional amplifiers to the antennas in the previously describedcircuits.

[0257] Typically, in the transmitter subsystem of a communicationssystem, upconverting the information signal to broadcast frequencyrequires, at least, filters, amplifiers, and frequency multipliers. Eachof these components is costly, not only in terms of the purchase priceof the component, but also because of the power required to operatethem.

[0258] The present invention provides a more efficient means forproducing a modulated carrier for transmission, uses less power, andrequires fewer components. These and additional advantages of thepresent invention will be apparent from the following description.

[0259] 3. Frequency Up-conversion.

[0260] The present invention is directed to systems and methods forfrequency up-conversion and applications of the same. In one embodiment,the frequency up-converter of the present invention allows the use of astable, low frequency oscillator to generate a stable high frequencysignal that, for example and without limitation, can be used as areference signal in a phase comparator or a frequency comparator. Inanother embodiment, the up-converter of the present invention is used ina transmitter. The invention is also directed to a transmitter. Based onthe discussion contained herein, one skilled in the relevant art(s) willrecognize that there are other, alternative embodiments and applicationsin which the frequency up-converter of the present invention could beused, and that these alternative embodiments and applications fallwithin the scope of the present invention.

[0261] For illustrative purposes, frequency up-conversion according tothe present invention is described below in the context of atransmitter. However, as apparent from the preceding paragraph, theinvention is not limited to this embodiment.

[0262] The following sections describe methods related to a transmitterand frequency up-converter. Structural exemplary embodiments forachieving these methods are also described. It should be understood thatthe invention is not limited to the particular embodiments describedbelow. Equivalents, extensions, variations, deviations, etc., of thefollowing will be apparent to persons skilled in the relevant art(s)based on the teachings contained herein. Such equivalents, extensions,variations, deviations, etc., are within the scope and spirit of thepresent invention.

[0263] 3.1 High Level Description.

[0264] This section (including its subsections) provides a high-leveldescription of up-converting and transmitting signals according to thepresent invention. In particular, an operational process of frequencyup-conversion in the context of transmitting signals is described at ahigh-level. The operational process is often represented by flowcharts.The flowcharts are presented herein for illustrative purposes only, andare not limiting. In particular, the use of flowcharts should not beinterpreted as limiting the invention to discrete or digital operation.In practice, those skilled in the relevant art(s) will appreciate, basedon the teachings contained herein, that the invention can be achievedvia discrete operation, continuous operation, or any combinationthereof. Furthermore, the flow of control represented by the flowchartsis also provided for illustrative purposes only, and it will beappreciated by persons skilled in the relevant art(s) that otheroperational control flows are within the scope and spirit of theinvention.

[0265] Also, a structural implementation for achieving this process isdescribed at a high-level. This structural implementation is describedherein for illustrative purposes, and is not limiting. In particular,the process described in this section can be achieved using any numberof structural implementations, one of which is described in thissection. The details of such structural implementations will be apparentto persons skilled in the relevant art(s) based on the teachingscontained herein.

[0266] 3.1.1 Operational Description.

[0267] The flow chart 900 of FIG. 9 demonstrates the operational methodof frequency up-conversion in the context of transmitting a signalaccording to an embodiment of the present invention. The invention isdirected to both frequency up-conversion and transmitting signals asrepresented in FIG. 9. Representative waveforms for signals generated inflow chart 900 are depicted in FIG. 19. For purposes of illustrating thehigh level operation of the invention, frequency modulation of a digitalinformation signal is depicted. The invention is not limited to thisexemplary embodiment. One skilled in the relevant art(s) will appreciatethat other modulation modes could alternatively be used (as described inlater sections).

[0268] In step 902, an information signal 1902 (FIG. 19A) is generatedby a source. This information signal may be analog, digital, and anycombination thereof, or anything else that is desired to be transmitted,and is at the baseband frequency. As described below, the informationsignal 1902 is used to modulate an intermediate signal 1904.Accordingly, the information signal 1902 is also herein called amodulating baseband information signal. In the example of FIG. 19A, theinformation signal 1902 is illustrated as a digital signal. However, theinvention is not limited to this embodiment. As noted above, theinformation signal 1902 can be analog, digital, and/or any combinationthereof.

[0269] An oscillating signal 1904 (FIG. 19B) is generated in step 904.In step 906, the oscillating signal 1904 is modulated, where themodulation is a result of, and a function of, the information signal1902. Step 906 produces a modulated oscillating signal 1906 (FIG. 19C),also called a modulated intermediate signal. As noted above, theflowchart of FIG. 9 is being described in the context of an examplewhere the information signal 1902 is a digital signal. However,alternatively, the information signal 1902 can be analog or anycombination of analog and digital. Also, the example shown in FIG. 19uses frequency shift keying (FSK) as the modulation technique.Alternatively, any modulation technique (e.g., FM, AM, PM, ASK, PSK,etc., or any combination thereof) can be used. The remaining steps908-912 of the flowchart of FIG. 9 operate in the same way, whether theinformation signal 1902 is digital, analog, etc., or any combinationthereof, and regardless of what modulation technique is used.

[0270] A harmonically rich signal 1908 (FIG. 19D) is generated from themodulated signal 1906 in step 908. Signal 1908 has a substantiallycontinuous and periodically repeated waveform. In an embodiment, thewaveform of signal 1908 is substantially rectangular, as is seen in theexpanded waveform 1910 of FIG. 19E. One skilled in the relevant art(s)will recognize the physical limitations to and mathematical obstaclesagainst achieving an exact or perfect rectangular waveform and it is notthe intent or requirement of the present invention that a perfectrectangular waveform be generated or needed. However, for ease ofdiscussion, the term “rectangular waveform” will be used herein and willrefer to waveforms that are substantially rectangular, and will includebut will not be limited to those waveforms that are generally referredto as square waves or pulses. It should be noted that if the situationarises wherein a perfect rectangular waveform is proven to be bothtechnically and mathematically feasible, that situation will also fallwithin the scope and intent of this invention

[0271] A continuous periodic waveform (such as waveform 1908) iscomposed of a series of sinusoidal waves of specific amplitudes andphases, the frequencies of which are integer multiples of the repetitionfrequency of the waveform. (A waveform's repetition frequency is thenumber of times per second the periodic waveform repeats.) A portion ofthe waveform of signal 1908 is shown in an expanded view as waveform1910 of FIG. 19E. The first three sinusoidal components of waveform 1910(FIG. 19E) are depicted as waveforms 1912 a, b, & c of FIG. 19F andwaveforms 1914 a, b, & c of FIG. 19G. (In the examples of FIGS. 19F & G,the three sinusoidal components are shown separately. In 110 actuality,these waveforms, along with all the other sinusoidal components whichare not shown, occur simultaneously, as seen in FIG. 19H. Note that inFIG. 19H, the waveforms are shown simultaneously, but are not shownsummed. If waveforms 1912 and 1914 were shown summed, they would, in thelimit, i.e., with an infinite number of sinusoidal components, beidentical to the periodic waveform 1910 of FIG. 19E. For ease ofillustration, only the first three of the infinite number of sinusoidalcomponents are shown.) These sinusoidal waves are called harmonics, andtheir existence can be demonstrated both graphically and mathematically.Each harmonic (waveforms 1912 a, b, & c and 1914 a, b, & c) has the sameinformation content as does waveform 1910 (which has the sameinformation as the corresponding portion of waveform 1908). Accordingly,the information content of waveform 1908 can be obtained from any of itsharmonics. As the harmonics have frequencies that are integer multiplesof the repetition frequency of signal 1908, and since they have the sameinformation content as signal 1908 (as just stated), the harmonics eachrepresent an up-converted representation of signal 1908. Some of theharmonics are at desired frequencies (such as the frequencies desired tobe transmitted). These harmonics are called “desired harmonics” or“wanted harmonics.” According to the invention, desired harmonics havesufficient amplitude for accomplishing the desired processing (i.e.,being transmitted). Other harmonics are not at the desired frequencies.These harmonics are called “undesired harmonics” or “unwantedharmonics.”

[0272] In step 910, any unwanted harmonics of the continuous periodicwaveform of signal 1908 are filtered out (for example, any harmonicsthat are not at frequencies desired to be transmitted). In the exampleof FIG. 19, the first and second harmonics (i.e., those depicted bywaveforms 1912 a & b of FIGS. 19F and 1914a & b of FIG. 19G) are theunwanted harmonics. In step 912, the remaining harmonic, in the exampleof FIG. 19, the third harmonic (i.e., those depicted by waveforms 1912 cof FIGS. 19F and 1914c of FIG. 19G), is transmitted. This is depicted bywaveform 1918 of FIG. 19I. In the example of FIG. 19, only threeharmonics are shown, and the lowest two are filtered out to leave thethird harmonic as the desired harmonic. In actual practice, there are aninfinite number of harmonics, and the filtering can be made to removeunwanted harmonics that are both lower in frequency than the desiredharmonic as well as those that are higher in frequency than the desiredharmonic.

[0273] 3.1.2 Structural Description.

[0274]FIG. 10 is a block diagram of an up-conversion system according toan embodiment of the invention. This embodiment of the up-conversionsystem is shown as a transmitter 1000. Transmitter 1000 includes anacceptance module 1004, a harmonic generation and extraction module1006, and a transmission module 1008 that accepts an information signal1002 and outputs a transmitted signal 1014.

[0275] Preferably, the acceptance module 1004, harmonic generation andextraction module 1006, and transmission module 1008 process theinformation signal in the manner shown in the operational flowchart 900.In other words, transmitter 1000 is the structural embodiment forperforming the operational steps of flowchart 900. However, it should beunderstood that the scope and spirit of the present invention includesother structural embodiments for performing the steps of flowchart 900.The specifics of these other structural embodiments will be apparent topersons skilled in the relevant art(s) based on the discussion containedherein.

[0276] The operation of the transmitter 1000 will now be described indetail with reference to the flowchart 900. In step 902, an informationsignal 1002 (for example, see FIG. 19A) from a source (not shown) isrouted to acceptance module 1004. In step 904, an oscillating signal(for example, see FIG. 19B) is generated and in step 906, it ismodulated, thereby producing a modulated signal 1010 (for an example ofFM, see FIG. 19C). The oscillating signal can be modulated using anymodulation technique, examples of which are described below. In step908, the harmonic generation and extraction module (HGEM) generates aharmonically rich signal with a continuous and periodic waveform (anexample of FM can be seen in FIG. 19D). This waveform is preferably arectangular wave, such as a square Wave or a pulse (although, theinvention is not limited to this embodiment), and is comprised of aplurality of sinusoidal waves whose frequencies are integer multiples ofthe fundamental frequency of the waveform. These sinusoidal waves arereferred to as the harmonics of the underlying waveform. A Fourierseries analysis can be used to determine the amplitude of each harmonic(for example, see FIGS. 19F and 19G). In step 910, a filter (not shown)within HGEM 1006 filters out the undesired frequencies (harmonics), andoutputs an electromagnetic (EM) signal 1012 at the desired frequency(for example, see FIG. 191). In step 912, EM signal 1012 is routed totransmission module 1008 (optional), where it is prepared fortransmission. The transmission module 1008 then outputs a transmittedsignal 1014.

[0277] 3.2 Exemplary Embodiments.

[0278] Various embodiments related to the method(s) and structure(s)described above are presented in this section (and its subsections).These embodiments are described herein for purposes of illustration, andnot limitation. The invention is not limited to these embodiments.Alternate embodiments (including equivalents, extensions, variations,deviations, etc., of the embodiments described herein) will be apparentto persons skilled in the relevant art(s) based on the teachingscontained herein. The invention is intended and adapted to include suchalternate embodiments.

[0279] 3.2.1 First Embodiment: Frequency Modulation (FM) Mode.

[0280] In this embodiment, an information signal is accepted and amodulated signal whose frequency varies as a function of the informationsignal results.

[0281] 3.2.1.1 Operational Description.

[0282] The flow chart of FIG. 1I demonstrates the method of operation ofa transmitter in the frequency modulation (FM) mode according to anembodiment of the present invention. As stated above, the representativewaveforms shown in FIG. 19 depict the invention operating as atransmitter in the FM mode.

[0283] In step 1102, an information signal 1902 (FIG. 19A) is generatedby a source by any means and/or process. (Information signal 1902 is abaseband signal, and, because it is used to modulate a signal, may alsobe referred to as a modulating baseband signal 1902.) Information signal1902 may be, for example, analog, digital, or any combination thereof.The signals shown in FIG. 19 depict a digital information signal whereinthe information is represented by discrete states of the signal. It willbe apparent to persons skilled in the relevant art(s) that the inventionis also adapted to working with an analog information signal wherein theinformation is represented by a continuously varying signal. In step1104, information signal 1902 modulates an oscillating signal 1904 (FIG.19B). The result of this modulation is the modulated signal 1906 (FIG.19C) as indicated in block 1106. Modulated signal 1906 has a frequencythat varies as a function of information signal 1902 and is referred toas an FM signal.

[0284] In step 1108, a harmonically rich signal with a continuousperiodic waveform, shown in FIG. 19D as rectangular waveform 1908, isgenerated. Rectangular waveform 1908 is generated using the modulatedsignal 1906. One skilled in the relevant art(s) will recognize thephysical limitations to and mathematical obstacles against achieving anexact or perfect rectangular waveform and it is not the intent of thepresent invention that a perfect rectangular waveform be generated orneeded. Again, as stated above, for ease of discussion, the term“rectangular waveform” will be used to refer to waveforms that aresubstantially rectangular. In a similar manner, the term “square wave”will refer to those waveforms that are substantially square and it isnot the intent of the present invention that a perfect square wave begenerated or needed. A portion of rectangular waveform 1908 is shown inan expanded view as periodic waveform 1910 in FIG. 19E. The first partof waveform 1910 is designated “signal A” and represents informationsignal 1902 being “high,” and the second part of waveform 1910 isdesignated “signal B” and information signal 1902 being “low.” It shouldbe noted that this convention is used for illustrative purposes only,and alternatively, other conventions could be used.

[0285] As stated before, a continuous and periodic waveform, such as arectangular wave 1908 as indicated in block 1110 of flowchart 1100, hassinusoidal components (harmonics) at frequencies that are integermultiples of the fundamental frequency of the underlying waveform (i.e.,at the Fourier component frequencies). Three harmonics of periodicwaveform 1910 are shown separately, in expanded views, in FIGS. 19F and19G. Since waveform 1910 (and also waveform 1908) is shown as a squarewave in this exemplary embodiment, only the odd harmonics are present,i.e., the first, third, fifth, seventh, etc. As shown in FIG. 19, ifrectangular waveform 1908 has a fundamental frequency of f₁ (also knownas the first harmonic), the third harmonic will have a frequency of3·f₁, the fifth harmonic will have a frequency of 5·f₁, and so on. Thefirst, third, and fifth harmonics of signal A are shown as waveforms1912 a, 1912 b, and 1912 c of FIG. 19F, and the first, third, and fifthharmonics of signal B are shown as waveforms 1914 a, 1914 b, and 1914 cof FIG. 19G. In actuality, these harmonics (as well as all of the higherorder harmonics) occur simultaneously, as shown by waveform 1916 of FIG.19H. Note that if all of the harmonic components of FIG. 19H were shownsummed together with all of the higher harmonics (i.e., the seventh, theninth, etc.) the resulting waveform would, in the limit, be identical towaveform 1910.

[0286] In step 1112, the unwanted frequencies of waveform 1916 areremoved. In the example of FIG. 19, the first and third harmonics areshown to be removed, and as indicated in block 1114, the remainingwaveform 1918 (i.e., waveforms 1912 c and 1914 c) is at the desired EMfrequency. Although not shown, the higher harmonics (e.g., the seventh,ninth, etc.) are also removed.

[0287] The EM signal, shown here as remaining waveform 1918, is preparedfor transmission in step 1116, and in step 1118, the EM signal istransmitted.

[0288] 3.2.1.2 Structural Description.

[0289]FIG. 12 is a block diagram of a transmitter according to anembodiment of the invention. This embodiment of the transmitter is shownas an FM transmitter 1200. FM transmitter 1200 includes a voltagecontrolled oscillator (VCO) 1204, a switch module 1214, a filter 1218,and a transmission module 1222 that accepts an information signal 1202and outputs a transmitted signal 1224. The operation and structure ofexemplary components are described below: an exemplary VCO is describedbelow at sections 3.3.1-3.3.1.2; an exemplary switch module is describedbelow at sections 3.3.6-3.3.6.2; an exemplary filter is described belowat sections 3.3.9-3.3.9.2; and an exemplary transmission module isdescribed below at sections 3.3.10-3.3.10.2.

[0290] Preferably, the voltage controlled oscillator 1204, switch module1214, filter 1218, and transmission module 1222 process the informationsignal in the manner shown in the operational flowchart 1100. In otherwords, FM transmitter 1200 is the structural embodiment for performingthe operational steps of flowchart 1100. However, it should beunderstood that the scope and spirit of the present invention includesother structural embodiments for performing the steps of flowchart 1100.The specifics of these other structural embodiments will be apparent topersons skilled in the relevant art(s) based on the discussion containedherein.

[0291] The operation of the transmitter 1200 will now be described indetail with reference to the flowchart 1100. In step 1102, aninformation signal 1202 (for example, see FIG. 19A) from a source (notshown) is routed to VCO 1204. In step 1104, an oscillating signal (forexample, see FIG. 19B) is generated and modulated, thereby producing afrequency modulated signal 1210 (for example, see FIG. 19C). In step1108, the switch module 1214 generates a harmonically rich signal 1216with a continuous and periodic wavef6rm (for example, see FIG. 19D).This waveform is preferably a rectangular wave, such as a square wave ora pulse (although, the invention is not limited to this embodiment), andis comprised of a plurality of sinusoidal waves whose frequencies areinteger multiples of the fundamental frequency of the waveform. Thesesinusoidal waves are referred to as the harmonics of the underlyingwaveform, and a Fourier analysis will determine the amplitude of eachharmonic (for example, see FIGS. 19F and 19G). In step 1112, a filter1218 filters out the undesired frequencies (harmonics), and outputs anelectromagnetic (EM) signal 1220 at the desired harmonic frequency (forexample, see FIG. 191). In step 1116, EM signal 1220 is routed totransmission module 1222 (optional), where it is prepared fortransmission. In step 1118, transmission module 1222 outputs atransmitted signal 1224.

[0292] 3.2.2 Second Embodiment: Phase Modulation (PM) Mode.

[0293] In this embodiment, an information signal is accepted and amodulated signal whose phase varies as a function of the informationsignal is transmitted.

[0294] 3.2.2.1 Operational Description.

[0295] The flow chart of FIG. 13 demonstrates the method of operation ofthe transmitter in the phase modulation (PM) mode. The representativewaveforms shown in FIG. 44 depict the invention operating as atransmitter in the PM mode.

[0296] In step 1302, an information signal 4402 (FIG. 44A) is generatedby a source. Information signal 4402 may be, for example, analog,digital, or any combination thereof. The signals shown in FIG. 44 depicta digital information signal wherein the information is represented bydiscrete states of the signal. It will be apparent to persons skilled inthe relevant art(s) that the invention is also adapted to working withan analog information signal wherein the information is represented by acontinuously varying signal. In step 1304, an oscillating signal 4404 isgenerated and in step 1306, the oscillating signal 4404 (FIG. 44B) ismodulated by the information signal 4402, resulting in the modulatedsignal 4406 (FIG. 44C) as indicated in block 1308. The phase of thismodulated signal 4406 is varied as a function of the information signal4402.

[0297] A harmonically rich signal 4408 (FIG. 44D) with a continuousperiodic waveform is generated at step 1310 using modulated signal 4406.Harmonically rich signal 4408 is a substantially rectangular waveform.One skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving an exact orperfect rectangular waveform and it is not the intent of the presentinvention that a perfect rectangular waveform be generated or needed.Again, as stated above, for ease of discussion, the term “rectangularwaveform” will be used to refer to waveforms that are substantiallyrectangular. In a similar manner, the term “square wave” will refer tothose waveforms that are substantially square and it is not the intentof the present invention that a perfect square wave be generated orneeded. As stated before, a continuous and periodic waveform, such asthe harmonically rich signal 4408 as indicated in block 1312, hassinusoidal components (harmonics) at frequencies that are integermultiples of the fundamental frequency of the underlying waveform (theFourier component frequencies). The first three harmonic waveforms areshown in FIGS. 44E, 44F, and 44G. In actual fact, there are an infinitenumber of harmonics. In step 1314, the unwanted frequencies are removed,and as indicated in block 1316, the remaining frequency is at thedesired EM output. As an example, the first (fundamental) harmonic 4410and the second harmonic 4412 along with the fourth, fifth, etc.,harmonics (not shown) might be filtered out, leaving the third harmonic4414 as the desired EM signal as indicated in block 1316.

[0298] The EM signal is prepared for transmission in step 1318, and instep 1320, the EM signal is transmitted.

[0299] 3.2.2.2 Structural Description.

[0300]FIG. 14 is a block diagram of a transmitter according to anembodiment of the invention. This embodiment of the transmitter is shownas a PM transmitter 1400. PM transmitter 1400 includes a localoscillator 1406, a phase modulator 1404, a switch module 1410, a filter1414, and a transmission module 1418 that accepts an information signal1402 and outputs a transmitted signal 1420. The operation and structureof exemplary components are described below: an exemplary phasemodulator is described below at sections 3.3.4-3.3.4.2; an exemplarylocal oscillator is described below at sections 3.3.2-3.3.2.2; anexemplary switch module is described below at sections 3.3.6-3.3.6.2; anexemplary filter is described below at sections 3.3.9-3.3.9.2; and anexemplary transmission module is described below at sections3.3.10-3.3.10.2.

[0301] Preferably, the local oscillator 1406, phase modulator 1404,switch module 1410, filter 1414, and transmission module 1418 processthe information signal in the manner shown in the operational flowchart1300. In other words, PM transmitter 1400 is the structural embodimentfor performing the operational steps of flowchart 1300. However, itshould be understood that the scope and spirit of the present inventionincludes other structural embodiments for performing the steps offlowchart 1300. The specifics of these other structural embodiments willbe apparent to persons skilled in the relevant art(s) based on thediscussion contained herein.

[0302] The operation of the transmitter 1400 will now be described indetail with reference to the flowchart 1300. In step 1302, aninformation signal 1402 (for example, see FIG. 44A) from a source (notshown) is routed to phase modulator 1404. In step 1304, an oscillatingsignal from local oscillator 1406 (for example, see FIG. 44B) isgenerated and modulated, thereby producing a modulated signal 1408 (forexample, see FIG. 44C). In step 1310, the switch module 1410 generates aharmonically rich signal 1412 with a continuous and periodic waveform(for example, see FIG. 44D). This waveform is preferably a rectangularwave, such as a square wave or a pulse (although, the invention is notlimited to this embodiment), and is comprised of a plurality ofsinusoidal waves whose frequencies are integer multiples of thefundamental frequency of the waveform. These sinusoidal waves arereferred to as the harmonics of the underlying waveform, and a Fourieranalysis will determine the amplitude of each harmonic (for an exampleof the first three harmonics, see FIGS. 44E, 44F, and 44G). In step1314, a filter 1414 filters out the undesired harmonic frequencies (forexample, the first harmonic 4410, the second harmonic 4412, and thefourth, fifth, etc., harmonics, not shown), and outputs anelectromagnetic (EM) signal 1416 at the desired harmonic frequency (forexample, the third harmonic, see FIG. 44G). In step 1318, EM signal 1416is routed to transmission module 1418 (optional), where it is preparedfor transmission. In step 1320, the transmission module 1418 outputs atransmitted signal 1420.

[0303] 3.2.3 Third Embodiment: Amplitude Modulation (AM) Mode.

[0304] In this embodiment, an information signal is accepted and amodulated signal whose amplitude varies as a function of the informationsignal is transmitted.

[0305] 3.2.3.1 Operational Description.

[0306] The flow chart of FIG. 15 demonstrates the method of operation ofthe transmitter in the amplitude modulation (AM) mode. Therepresentative waveforms shown in FIG. 45 depict the invention operatingas a transmitter in the AM mode.

[0307] In step 1502, an information signal 4502 (FIG. 45A) is generatedby a source. Information signal 4502 may be, for example, analog,digital, or any combination thereof. The signals shown in FIG. 45 depicta digital information signal wherein the information is represented bydiscrete states of the signal. It will be apparent to persons skilled inthe relevant art(s) that the invention is also adapted to working withan analog information signal wherein the information is represented by acontinuously varying signal. In step 1504, a “reference signal” iscreated, which, as indicated in block 1506, has an amplitude that is afunction of the information signal 4502. In one embodiment of theinvention, the reference signal is created by combining the informationsignal 4502 with a bias signal. In another embodiment of the invention,the reference signal is comprised of only the information signal 4502.One skilled in the relevant art(s) will recognize that any number ofembodiments exist wherein the reference signal will vary as a functionof the information signal.

[0308] An oscillating signal 4504 (FIG. 45B) is generated at step 1508,and at step 1510, the reference signal (information signal 4502) isgated at a frequency that is a function of the oscillating signal 4504.The gated referenced signal is a harmonically rich signal 4506 (FIG.45C) with a continuous periodic waveform and is generated at step 1512.This harmonically rich signal 4506 as indicated in block 1514 issubstantially a rectangular wave which has a fundamental frequency equalto the frequency at which the reference signal (information signal 4502)is gated. In addition, the rectangular wave has pulse amplitudes thatare a function of the amplitude of the reference signal (informationsignal 4502). One skilled in the relevant art(s) will recognize thephysical limitations to and mathematical obstacles against achieving anexact or perfect rectangular waveform and it is not the intent of thepresent invention that a perfect rectangular waveform be generated orneeded. Again, as stated above, for ease of discussion, the term“rectangular waveform” will be used to refer to waveforms that aresubstantially rectangular. In a similar manner, the term “square wave”will refer to those waveforms that are substantially square and it isnot the intent of the present invention that a perfect square wave begenerated or needed.

[0309] As stated before, a harmonically rich signal 4506, such as therectangular wave as indicated in block 1514, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). The first three harmonic waveforms are shown in FIGS. 45D,45E, and 45F. In fact, there are an infinite number of harmonics. Instep 1516, the unwanted frequencies are removed, and as indicated inblock 1518, the remaining frequency is at the desired EM output. As anexample, the first (fundamental) harmonic 4510 and the second harmonic4512 along with the fourth, fifth, etc., harmonics (not shown) might befiltered out leaving the third harmonic 4514 as the desired EM signal asindicated in block 1518.

[0310] The EM signal is prepared for transmission in step 1520, and instep 1522, the EM signal is transmitted.

[0311] 3.2.3.2 Structural Description.

[0312]FIG. 16 is a block diagram of a transmitter according to anembodiment of the invention. This embodiment of the transmitter is shownas an AM transmitter 1600. AM transmitter 1600 includes a localoscillator 1610, a summing module 1606, a switch module 1614, a filter1618, and a transmission module 1622 that accepts an information signal1602 and outputs a transmitted signal 1624. The operation and structureof exemplary components are described below: an exemplary localoscillator is described below at sections 3.3.2-3.3.2.2; an exemplary aswitch module is described below at sections 3.3.7-3.3.7.2; an exemplaryfilter is described below at sections 3.3.9-3.3.9.2; and an exemplarytransmission module is described below at sections 3.3.10-3.3.10.2.

[0313] Preferably, the local oscillator 1610, summing module 1606,switch module 1614, filter 1618, and transmission module 1622 process aninformation signal 1602 in the manner shown in the operational flowchart1500. In other words, AM transmitter 1600 is the structural embodimentfor performing the operational steps of flowchart 1500. However, itshould be understood that the scope and spirit of the present inventionincludes other structural embodiments for performing the steps offlowchart 1500. The specifics of these other structural embodiments willbe apparent to persons skilled in the relevant art(s) based on thediscussion contained herein.

[0314] The operation of the transmitter 1600 will now be described indetail with reference to the flowchart 1500. In step 1502, informationsignal 1602 (for example, see FIG. 45A) from a source (not shown) isrouted to summing module 1606 (if required), thereby producing areference signal 1608. In step 1508, an oscillating signal 1612 isgenerated by local oscillator 1610 (for example, see FIG. 45B) and instep 1510, switch module 1614 gates the reference voltage 1608 at a ratethat is a function of the oscillating signal 1612. The result of thegating is a harmonically rich signal 1616 (for example, see FIG. 45C)with a continuous and periodic waveform. This waveform is preferably arectangular wave, such as a square wave or a pulse (although, theinvention is not limited to this embodiment), and is comprised of aplurality of sinusoidal waves whose frequencies are integer multiples ofthe fundamental frequency of the waveform. These sinusoidal waves arereferred to as the harmonics of the underlying waveform, and a Fourieranalysis will determine the relative amplitude of each harmonic (for anexample of the first three harmonics, see FIGS. 45D, 45E, and 45F). Whenamplitude modulation is applied, the amplitude of the pulses inrectangular waveform 1616 vary as a function of reference signal 1608.As a result, this change in amplitude of the pulses has a proportionaleffect on the absolute amplitude of all of the harmonics. In otherwords, the AM is embedded on top of each of the harmonics. In step 1516,a filter 1618 filters out the undesired harmonic frequencies (forexample, the first harmonic 4510, the second harmonic 4512, and thefourth, fifth, etc., harmonics, not shown), and outputs anelectromagnetic (EM) signal 1620 at the desired harmonic frequency (forexample, the third harmonic, see FIG. 45F). In step 1520, EM signal 1620is routed to transmission module 1622 (optional), where it is preparedfor transmission. In step 1522, the transmission module 1622 outputs atransmitted signal 1624.

[0315] Note that the description of the AM embodiment given herein showsthe information signal being gated, thus applying the amplitudemodulation to the harmonically rich signal. However, is would beapparent based on the teachings contained herein, that the informationsignal can be modulated onto the harmonically rich signal or onto afiltered harmonic at any point in the circuit.

[0316] 3.2.4 Fourth Embodiment: In-Phase/Quadrature-Phase Modulation(“I/Q “) Mode.

[0317] In-phase/quadrature-phase modulation (“I/Q”) is a specific subsetof a phase modulation (PM) embodiment. Because “I/Q” is so pervasive, itis described herein as a separate embodiment. However, it should beremembered that since it is a specific subset of PM, the characteristicsof PM also apply to In this embodiment, two information signals areaccepted. An in-phase signal (“I”) is modulated such that its phasevaries as a function of one of the information signals, and aquadrature-phase signal (“Q”) is modulated such that its phase varies asa function of the other information signal. The two modulated signalsare combined to form an “I/Q” modulated signal and transmitted.

[0318] 3.2.4.1 Operational Description.

[0319] The flow chart of FIG. 17 demonstrates the method of operation ofthe transmitter in the in-phase/quadrature-phase modulation (“I/Q”)mode. In step 1702, a first information signal is generated by a firstsource. This information signal may be analog, digital, or anycombination thereof. In step 1710, an in-phase oscillating signal(referred to as the “I” signal) is generated and in step 1704, it ismodulated by the first information signal. This results in the “I”modulated signal as indicated in block 1706 wherein the phase of the “I”modulated signal is varied as a function of the first informationsignal.

[0320] In step 1714, a second information signal is generated. Again,this signal may be analog, digital, or any combination thereof, and maybe different than the first information signal. In step 1712, the phaseof “I” oscillating signal generated in step 1710 is shifted, creating aquadrature-phase oscillating signal (referred to as the “Q” signal). Instep 1716, the “Q” signal is modulated by the second information signal.This results in the “Q” modulated signal as indicated in block 1718wherein the phase of the “Q” modulated signal is varied as a function ofthe second information signal.

[0321] An “I” signal with a continuous periodic waveform is generated atstep 1708 using the “I” modulated signal, and a “Q” signal with acontinuous periodic waveform is generated at step 1720 using the “Q”modulated signal. In step 1722, the “I” periodic waveform and the “Q”periodic waveform are combined forming what is referred to as the “I/Q”periodic waveform as indicated in block 1724. As stated before, acontinuous and periodic waveform, such as a “IQ” rectangular wave asindicated in block 1724, has sinusoidal components (harmonics) atfrequencies that are integer multiples of the fundamental frequency ofthe underlying waveform (the Fourier component frequencies). In step1726, the unwanted frequencies are removed, and as indicated in block1728, the remaining frequency is at the desired EM output.

[0322] The “I/Q” EM signal is prepared for transmission in step 1730,and in step 1732, the “I/Q” EM signal is transmitted.

[0323] 3.2.4.2 Structural Description.

[0324]FIG. 18 is a block diagram of a transmitter according to anembodiment of the invention. This embodiment of the transmitter is shownas an “I/Q” transmitter 1800. “I/Q” transmitter 1800 includes a localoscillator 1806, a phase shifter 1810, two phase modulators 1804 & 1816,two switch modules 1822 & 1828, a summer 1832, a filter 1836, and atransmission module 1840. The “I/Q” transmitter accepts two informationsignals 1802 & 1814 and outputs a transmitted signal 1420. The operationand structure of exemplary components are described below: an exemplaryphase modulator is described below at sections 3.3.4-3.3.4.2; anexemplary local oscillator is described below at sections 3.3.2-3.3.2.2;an exemplary phase shifter is described below at sections 3.3.3-3.3.3.2;an exemplary switch module is described below at sections 3.3.6-3.3.6.2;an exemplary summer is described below at sections 3.3.8-3.3.8.2; anexemplary filter is described below at sections 3.3.9-3.3.9.2; and anexemplary transmission module is described below at sections3.3.10-3.3.10.2.

[0325] Preferably, the local oscillator 1806, phase shifter 1810, phasemodulators 1804 & 1816, switch modules 1822 & 1828, summer 1832, filter1836, and transmission module 1840 process the information signal in themanner shown in the operational flowchart 1700. In other words, “I/Q”transmitter 1800 is the structural embodiment for performing theoperational steps of flowchart 1700. However, it should be understoodthat the scope and spirit of the present invention includes otherstructural embodiments for performing the steps of flowchart 1700. Thespecifics of these other structural embodiments will be apparent topersons skilled in the relevant art(s) based on the discussion containedherein.

[0326] The operation of the transmitter 1800 will now be described indetail with reference to the flowchart 1700 In step 1702, a firstinformation signal 1802 from a source (not shown) is routed to the firstphase modulator 1804. In step 1710, an “I” oscillating signal 1808 fromlocal oscillator 1806 is generated and in step 1704, “I” oscillatingsignal 1808 is modulated by first information signal 1802 in the firstphase modulator 1804, thereby producing an “I” modulated signal 1820. Instep 1708, the first switch module 1822 generates a harmonically rich“I” signal 1824 with a continuous and periodic waveform.

[0327] In step 1714, a second information signal 1814 from a source (notshown) is routed to the second phase modulator 1816. In step 1712, thephase of oscillating signal 1808 is shifted by phase shifter 1810 tocreate “Q” oscillating signal 1812. In step 1716, “Q” oscillating signal1812 is modulated by second information signal 1814 in the second phasemodulator 1816, thereby producing “Q” modulated signal 1826. In step1720, the second switch module 1828 generates a harmonically rich “Q”signal 1830 with a continuous and periodic waveform. Harmonically rich“I” signal 1824 and harmonically rich “Q” signal 1830 are preferablyrectangular waves, such as square waves or pulses (although, theinvention is not limited to this embodiment), and are comprised ofpluralities of sinusoidal waves whose frequencies are integer multiplesof the fundamental frequency of the waveforms. These sinusoidal wavesare referred to as the harmonics of the underlying waveforms, and aFourier analysis will determine the amplitude of each harmonic.

[0328] In step 1722, harmonically rich “I” signal 1824 and harmonicallyrich “Q” signal 1830 are combined by summer 1832 to create harmonicallyrich “I/Q” signal 1834. In step 1726, a filter 1836 filters out theundesired harmonic frequencies, and outputs an “I/Q” electromagnetic(EM) signal 1838 at the desired harmonic frequency. In step 1730, “I/Q”EM signal 1838 is routed to transmission module 1840 (optional), whereit is prepared for transmission. In step 1732, the transmission module1840 outputs a transmitted signal 1842.

[0329] It will be apparent to those skilled in the relevant art(s) thatan alternate embodiment exists wherein the harmonically rich “I” signal1824 and the harmonically rich “Q” signal 1830 may be filtered beforethey are summed, and further, another alternate embodiment existswherein “I” modulated signal 1820 and “Q” modulated signal 1826 may besummed to create an “I/Q” modulated signal before being routed to aswitch module.

[0330] 3.2.5 Other Embodiments.

[0331] Other embodiments of the up-converter of the present inventionbeing used as a transmitter (or in other applications) may use subsetsand combinations of modulation techniques. These would be apparent toone skilled in the relevant art(s) based on the teachings disclosedherein, and include, but are not limited to, quadrature amplitudemodulation (QAM), and embedding two forms of modulation onto a signalfor up-conversion.

[0332] An exemplary circuit diagram illustrating the combination of twomodulations is found in FIG. 62. This example uses AM combined with PM.The waveforms shown in FIG. 63 illustrate the phase modulation of adigital information signal “A” 6202 combined with the amplitudemodulation of an analog information signal “B” 6204. An oscillatingsignal 6216 (FIG. 63B) and information signal “A” 6202 (FIG. 63A) arereceived by phase modulator 1404, thereby creating a phase modulatedsignal 6208 (FIG. 63C). Note that for illustrative purposes, and notlimiting, the information signal is shown as a digital signal, and thephase modulation is shown as shifting the phase of the oscillatingsignal by 180°. Those skilled in the relevant art(s) will appreciatethat the information signal could be analog (although typically it isdigital), and that phase modulations other than 180° may also be used.FIG. 62 shows a pulse shaper 6216 receiving phase modulated signal 6208and outputting a pulse-shaped PM signal 6210. The pulse shaper isoptional, depending on the selection and design of the phase modulator1404. Information signal “B” 6304 and bias signal 1604 (if required) arecombined by summing module 1606 (optional) to create reference signal6206 (FIG. 63E). Pulse-shaped PM signal 6210 is routed to switch module1410, 1614 where it gates the reference signal 6206 thereby producing aharmonically rich signal 6212 (FIG. 63F). It can be seen that theamplitude of harmonically rich signal 6212 varies as a function ofreference signal 6206, and the period and pulse width of harmonicallyrich signal 6212 are substantially the same as pulse-shaped PM signal6210. FIG. 63 only illustrates the fundamental and second harmonics ofharmonically rich signal 6212. In fact, there may be an infinite numberof harmonics, but for illustrative purposes (and not limiting) the firsttwo harmonics are sufficient to illustrate that both the phasemodulation and the amplitude modulation that are present on theharmonically rich signal 6212 are also present on each of the harmonics.Filter 1414, 1618 will remove the unwanted harmonics, and a desiredharmonic 6214 is routed to transmission module 1418, 1622 (optional)where it is prepared for transmission. Transmission module 1418, 1622then outputs a transmitted signal 1420, 1624. Those skilled in therelevant art(s) will appreciate that these examples are provided forillustrative purposes only and are not limiting.

[0333] The embodiments described above are provided for purposes ofillustration. These embodiments are not intended to limit the invention.Alternate embodiments, differing slightly or substantially from thosedescribed herein, will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternateembodiments include, but are not limited to, combinations of modulationtechniques in an “I/Q” mode. Such alternate embodiments fall within thescope and spirit of the present invention.

[0334] 3.3 Methods and Systems for Implementing the Embodiments.

[0335] Exemplary operational and/or structural implementations relatedto the method(s), structure(s), and/or embodiments described above arepresented in this section (and its subsections). These components andmethods are presented herein for purposes of illustration, and notlimitation. The invention is not limited to the particular examples ofcomponents and methods described herein. Alternatives (includingequivalents, extensions, variations, deviations, etc., of thosedescribed herein) will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternatives fallwithin the scope and spirit of the present invention.

[0336] 3.3.1 The Voltage Controlled Oscillator (FM Mode).

[0337] As discussed above, the frequency modulation (FM) mode embodimentof the invention uses a voltage controlled oscillator (VCO). See, as anexample, VCO 1204 in FIG. 12. The invention supports numerousembodiments of the VCO. Exemplary embodiments of the VCO 2304 (FIG. 23)are described below. However, it should be understood that theseexamples are provided for illustrative purposes only. The invention isnot limited to these embodiments.

[0338] 3.3.1.1 Operational Description.

[0339] The information signal 2302 is accepted and an oscillating signal2306 whose frequency varies as a function of the information signal 2302is created. Oscillating signal 2306 is also referred to as frequencymodulated intermediate signal 2306. The information signal 2302 may beanalog or digital or a combination thereof, and may be conditioned toensure it is within the desired range.

[0340] In the case where the information signal 2302 is digital, theoscillating signal 2306 may vary between discrete frequencies. Forexample, in a binary system, a first frequency corresponds to a digital“high,” and a second frequency corresponds to a digital “low.” Eitherfrequency may correspond to the “high” or the “low,” depending on theconvention being used. This operation is referred to as frequency shiftkeying (FSK) which is a subset of FM. If the information signal 2302 isanalog, the frequency of the oscillating signal 2306 will vary as afunction of that analog signal, and is not limited to the subset of FSKdescribed above.

[0341] The oscillating signal 2306 is a frequency modulated signal whichcan be a sinusoidal wave, a rectangular wave, a triangular wave, apulse, or any other continuous and periodic waveform. As stated above,one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed. Again, as stated above, forease of discussion, the term “rectangular waveform” will be used torefer to waveforms that are substantially rectangular, the term “squarewave” will refer to those waveforms that are substantially square, theterm “triangular wave” will refer to those waveforms that aresubstantially triangular, and the term “pulse” will refer to thosewaveforms that are substantially a pulse, and it is not the intent ofthe present invention that a perfect square wave, triangle wave, orpulse be generated or needed.

[0342] 3.3.1.2 Structural Description.

[0343] The design and use of a voltage controlled oscillator 2304 iswell known to those skilled in the relevant art(s). The VCO 2304 may bedesigned and fabricated from discrete components, or it may be purchased“off the shelf.” VCO 2304 accepts an information signal 2302 from asource. The information signal 2302 is at baseband and generally is anelectrical signal within a prescribed voltage range. If the informationis digital, the voltage will be at discrete levels. If the informationis analog, the voltage will be continuously variable between an upperand a lower level. The VCO 2304 uses the voltage of the informationsignal 2302 to cause a modulated oscillating signal 2306 to be output.The information signal 2302, because it is a baseband signal and is usedto modulate the oscillating signal, may be referred to as the modulatingbaseband signal 2302.

[0344] The frequency of the oscillating signal 2306 varies as a functionof the voltage of the modulating baseband signal 2302. If the modulatingbaseband signal 2302 represents digital information, the frequency ofthe oscillating signal 2306 will be at discrete levels. If, on the otherhand, the modulating baseband signal 2302 represents analog information,the frequency of the oscillating signal 2306 will be continuouslyvariable between its higher and lower frequency limits. The oscillatingsignal 2306 can be a sinusoidal wave, a rectangular wave, a triangularwave, a pulse, or any other continuous and periodic waveform.

[0345] The frequency modulated oscillating signal 2306 may then be usedto drive a switch module 2802.

[0346] 3.3.2 The Local Oscillator (PM, AM, and “I/Q” Modes).

[0347] As discussed above, the phase modulation (PM) and amplitudemodulation (AM) mode embodiments of the invention use a localoscillator. So too does the in-phase/quadrature-phase modulation (“I/Q”)mode embodiment. See, as an example, local oscillator 1406 in FIG. 14,local oscillator 1610 in FIG. 16, and local oscillator 1806 in FIG. 18.The invention supports numerous embodiments of the local oscillator.Exemplary embodiments of the local oscillator 2402 (FIG. 24) aredescribed below. However, it should be understood that these examplesare provided for illustrative purposes only. The invention is notlimited to these embodiments.

[0348] 3.3.2.1 Operational Description.

[0349] An oscillating signal 2404 is generated. The frequency of thesignal 2404 may be selectable, but generally is not considered to be“variable.” That is, the frequency may be selected to be a specificvalue for a specific implementation, but generally it does not vary as afunction of the information signal 2302 (i.e., the modulating basebandsignal).

[0350] The oscillating signal 2404 generally is a sinusoidal wave, butit may also be a rectangular wave, a triangular wave, a pulse, or anyother continuous and periodic waveform. As stated above, one skilled inthe relevant art(s) will recognize the physical limitations to andmathematical obstacles against achieving exact or perfect waveforms andit is not the intent of the present invention that a perfect waveform begenerated or needed. Again, as stated above, for ease of discussion, theterm “rectangular waveform” will be used to refer to waveforms that aresubstantially rectangular, the term “square wave” will refer to thosewaveforms that are substantially square, the term “triangular wave” willrefer to those waveforms that are substantially triangular, and the term“pulse” will refer to those waveforms that are substantially a pulse,and it is not the intent of the present invention that a perfect squarewave, triangle wave, or pulse be generated or needed.

[0351] 3.3.2.2 Structural Description.

[0352] The design and use of a local oscillator 2402 is well known tothose skilled in the relevant art(s). A local oscillator 2402 may bedesigned and fabricated from discrete components or it may be purchased“off the shelf.” A local oscillator 2402 is generally set to output aspecific frequency. The output can be “fixed” or it can be “selectable,”based on the design of the circuit. If it is fixed, the output isconsidered to be substantially a fixed frequency that cannot be changed.If the output frequency is selectable, the design of the circuit willallow a control signal to be applied to the local oscillator 2402 tochange the frequency for different applications. However, the outputfrequency of a local oscillator 2402 is not considered to be “variable”as a function of an information signal 2302 such as the modulatingbaseband signal 2302. (If it were desired for the output frequency of anoscillator to be variable as a function of an information signal, a VCOwould preferably be used.) The oscillating signal 2404 generally is asinusoidal wave, but it may also be a rectangular wave, a triangularwave, a pulse, or any other continuous and periodic waveform.

[0353] The output of a local oscillator 2402 may be an input to othercircuit components such as a phase modulator 2606, a phase shiftingcircuit 2504, switch module 3102, etc.

[0354] 3.3.3 The Phase Shifter (“I/Q” Mode).

[0355] As discussed above, the in-phase/quadrature-phase modulation(“I/Q”) mode embodiment of the invention uses a phase shifter. See, asan example, phase shifter 1810 in FIG. 18. The invention supportsnumerous embodiments of the phase shifter. Exemplary embodiments of thephase shifter 2504 (FIG. 25) are described below. The invention is notlimited to these embodiments. The description contained herein is for a“90° phase shifter.” The 90° phase shifter is used for ease ofexplanation, and one skilled in the relevant art(s) will understand thatother phase shifts can be used without departing from the intent of thepresent invention.

[0356] 3.3.3.1 Operational Description.

[0357] An “in-phase” oscillating signal 2502 is received and a“quadrature-phase” oscillating signal 2506 is output. If the in-phase(“I”) signal 2502 is referred to as being a sine wave, then thequadrature-phase (“Q”) signal 2506 can be referred to as being a cosinewave (i.e., the “Q” signal 2506 is 90° out of phase with the “I” signal2502). However, they may also be rectangular waves, triangular waves,pulses, or any other continuous and periodic waveforms. As stated above,one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed. Again, as stated above, forease of discussion, the term “rectangular waveform” will be used torefer to waveforms that are substantially rectangular, the term “squarewave” will refer to those waveforms that are substantially square, theterm “triangular wave” will refer to those waveforms that aresubstantially triangular, and the term “pulse” will refer to thosewaveforms that are substantially a pulse, and it is not the intent ofthe present invention that a perfect square wave, triangle wave, orpulse be generated or needed. Regardless of the shapes of the waveforms,the “Q” signal 2506 is out of phase with the “I” signal 2506 byone-quarter period of the waveform. The frequency of the “I” and “Q”signals 2502 and 2506 are substantially equal.

[0358] The discussion contained herein will be confined to the moreprevalent embodiment wherein there are two intermediate signalsseparated by 90°. This is not limiting on the invention. It will beapparent to those skilled in the relevant art(s) that the techniquestough herein and applied to the “I/Q” embodiment of the presentinvention also apply to more exotic embodiments wherein the intermediatesignals are shifted by some amount other than 90°, and also whereinthere may be more than two intermediate frequencies.

[0359] 3.3.3.2 Structural Description.

[0360] The design and use of a phase shifter 2504 is well known to thoseskilled in the relevant art(s). A phase shifter 2504 may be designed andfabricated from discrete components or it may be purchased “off theshelf.” A phase shifter accepts an “in-phase” (“I”) oscillating signal2502 from any of a number of sources, such as a VCO 2304 or a localoscillator 2402, and outputs a “quadrature-phase” (“Q”) oscillatingsignal 2506 that is substantially the same frequency and substantiallythe same shape as the incoming “I” signal 2502, but with the phaseshifted by 90°. Both the “I” and “Q” signals 2502 and 2506 are generallysinusoidal waves, but they may also be rectangular waves, triangularwaves, pulses, or any other continuous and periodic waveforms.Regardless of the shapes of the waveforms, the “Q” signal 2506 is out ofphase with the “I” signal 2502 by one-quarter period of the waveform.Both the “I” and “Q” signals 2502 and 2506 may be modulated.

[0361] The output of a phase shifter 2504 may be used as an input to aphase modulator 2606.

[0362] 3.3.4 The Phase Modulator (PM and “I/Q” Modes).

[0363] As discussed above, the phase modulation (PM) mode embodimentincluding the in-phase/quadrature-phase modulation (“I/Q”) modeembodiment of the invention uses a phase modulator. See, as an example,phase modulator 1404 of FIG. 14 and phase modulators 1804 and 1816 ofFIG. 18. The invention supports numerous embodiments of the phasemodulator. Exemplary embodiments of the phase modulator 2606 (FIG. 26)are described below. However, it should be understood that theseexamples are provided for illustrative purposes only. The invention isnot limited to these embodiments.

[0364] 3.3.4.1 Operational Description.

[0365] An information signal 2602 and an oscillating signal 2604 areaccepted, and a phase modulated oscillating signal 2608 whose phasevaries as a function of the information signal 2602 is output. Theinformation signal 2602 may be analog or digital and may be conditionedto ensure it is within the desired range. The oscillating signal 2604can be a sinusoidal wave, a rectangular wave, a triangular wave, apulse, or any other continuous and periodic waveform. As stated above,one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed. Again, as stated above, forease of discussion, the term “rectangular waveform” will be used torefer to waveforms that are substantially rectangular, the term “squarewave” will refer to those waveforms that are substantially square, theterm “triangular wave” will refer to those waveforms that aresubstantially triangular, and the term “pulse” will refer to thosewaveforms that are substantially a pulse, and it is not the intent ofthe present invention that a perfect square wave, triangle wave, orpulse be generated or needed. The modulated oscillating signal 2608 isalso referred to as the modulated intermediate signal 2608.

[0366] In the case where the information signal 2602 is digital, themodulated intermediate signal 2608 will shift phase between discretevalues, the first phase (e.g., for a signal represented by sin(ωt+θ_(o))) corresponding to a digital “high,” and the second phase(e.g., for a signal represented by sin (ωt+θ_(o)+δ), where δ representsthe amount the phase has been shifted) corresponding to a digital “low.”Either phase may correspond to the “high” or the “low,” depending on theconvention being used. This operation is referred to as phase shiftkeying (PSK) which is a subset of PM.

[0367] If the information signal 2602 is analog, the phase of themodulated intermediate signal 2608 will vary as a function of theinformation signal 2602 and is not limited to the subset of PSKdescribed above.

[0368] The modulated intermediate signal 2608 is a phase modulatedsignal which can be a sinusoidal wave, a rectangular wave, a triangularwave, a pulse, or any other continuous and periodic waveform, and whichhas substantially the same period as the oscillating signal 2604.

[0369] 3.3.4.2 Structural Description.

[0370] The design and use of a phase modulator 2606 is well known tothose skilled in the relevant art(s). A phase modulator 2606 may bedesigned and fabricated from discrete components, or it may be purchased“off the shelf.” A phase modulator 2606 accepts an information signal2602 from a source and an oscillating signal 2604 from a localoscillator 2402 or a phase shifter 2504. The information signal 2602 isat baseband and is generally an electrical signal within a prescribedvoltage range. If the information is digital, the voltage will be atdiscrete levels. If the information is analog, the voltage will becontinuously variable between an upper and a lower level as a functionof the information signal 2602. The phase modulator 2606 uses thevoltage of the information signal 2602 to modulate the oscillatingsignal 2604 and causes a modulated intermediate signal 2608 to beoutput. The information signal 2602, because it is a baseband signal andis used to modulate the oscillating signal, may be referred to as themodulating baseband signal 2604.

[0371] The modulated intermediate signal 2608 is an oscillating signalwhose phase varies as a function of the voltage of the modulatingbaseband signal 2602. If the modulating baseband signal 2602 representsdigital information, the phase of the modulated intermediate signal 2608will shift by a discrete amount (e.g., the modulated intermediate signal2608 will shift by an amount δ between sin (ωt+θ_(o)) and sin(ωt+θ_(o)+δ)). If, on the other hand, the modulating baseband signal2602 represents analog information, the phase of the modulatedintermediate signal 2608 will continuously shift between its higher andlower phase limits as a function of the information signal 2602. In oneexemplary embodiment, the upper and lower limits of the modulatedintermediate signal 2608 can be represented as sin (ωt+θ_(o)) and sin(ω+θ_(o)+π). In other embodiments, the range of the phase shift may beless than π. The modulated intermediate signal 2608 can be a sinusoidalwave, a rectangular wave, a triangular wave, a pulse, or any othercontinuous and periodic waveform.

[0372] The phase modulated intermediate signal 2608 may then be used todrive a switch module 2802.

[0373] 3.3.5 The Summing Module (AM Mode).

[0374] As discussed above, the amplitude modulation (AM) mode embodimentof the invention uses a summing module. See, as an example, summingmodule 1606 in FIG. 16. The invention supports numerous embodiments ofthe summing module. Exemplary embodiments of the summing module 2706(FIG. 27) are described below. However, it should be understood thatthese examples are provided for illustrative purposes only. Theinvention is not limited to these embodiments. It may also be used inthe “I/Q” mode embodiment when the modulation is AM. The summing module2706 need not be used in all AM embodiments.

[0375] 3.3.5.1 Operational Description.

[0376] An information signal 2702 and a bias signal 2702 are accepted,and a reference signal is output. The information signal 2702 may beanalog or digital and may be conditioned to ensure it is within theproper range so as not to damage any of the circuit components. The biassignal 2704 is usually a direct current (DC) signal.

[0377] In the case where the information signal 2702 is digital, thereference signal 2706 shifts between discrete values, the first valuecorresponding to a digital “high,” and the second value corresponding toa digital “low.” Either value may correspond to the “high” or the “low,”depending on the convention being used. This operation is referred to asamplitude shift keying (ASK) which is a subset of AM.

[0378] If the information signal 2702 is analog, the value of thereference signal 2708 will vary linearly between upper and lowerextremes which correspond to the upper and lower limits of theinformation signal 2702. Again, either extreme of the reference signal2708 range may correspond to the upper or lower limit of the informationsignal 2702 depending on the convention being used.

[0379] The reference signal 2708 is a digital or analog signal and issubstantially proportional to the information signal 2702.

[0380] 3.3.5.2 Structural Description.

[0381] The design and use of a summing module 2706 is well known tothose skilled in the relevant art(s). A summing module 2706 may bedesigned and fabricated from discrete components, or it may be purchased“off the shelf.” A summing module 2706 accepts an information signal2702 from a source. The information signal 2702 is at baseband andgenerally is an electrical signal within a prescribed voltage range. Ifthe information is digital, the information signal 2702 is at either oftwo discrete levels. If the information is analog, the informationsignal 2702 is continuously variable between an upper and a lower level.The summing module 2706 uses the voltage of the information signal 2702and combines it with a bias signal 2704. The output of the summingmodule 2706 is called the reference signal 2708. The purpose of thesumming module 2706 is to cause the reference signal 2708 to be within adesired signal range. One skilled in the relevant art(s) will recognizethat the information signal 2702 may be used directly, without beingsummed with a bias signal 2704, if it is already within the desiredrange. The information signal 2702 is a baseband signal, but typically,in an AM embodiment, it is not used to directly modulate an oscillatingsignal. The amplitude of the reference signal 2708 is at discrete levelsif the information signal 2702 represents digital information. On theother hand, the amplitude of the reference signal 2708 is continuouslyvariable between its higher and lower limits if the information signal2702 represents analog information. The amplitude of the referencesignal 2708 is substantially proportional to the information signal2702, however, a positive reference signal 2708 need not represent apositive information signal 2702.

[0382] The reference signal 2708 is routed to the first input 3108 of aswitch module 3102. In one exemplary embodiment, a resistor 2824 isconnected between the output of the summing module 2706 (or the sourceof the information signal 2702 in the embodiment wherein the summingamplifier 2706 is not used) and the switch 3116 of the switch module3102.

[0383] 3.3.6 The Switch Module (FM, PM, and “I/Q” Modes).

[0384] As discussed above, the frequency modulation (FM), phasemodulation (PM), and the in-phase/quadrature-phase modulation (“I/Q”)mode embodiments of the invention use a switching assembly referred toas switch module 2802 (FIGS. 28A-28C). As an example, switch module 2802is a component in switch module 1214 in FIG. 12, switch module 1410 inFIG. 14, and switch modules 1822 and 1828 in FIG. 18. The inventionsupports numerous embodiments of the switch module. Exemplaryembodiments of the switch module 2802 are described below. However, itshould be understood that these examples are provided for illustrativepurposes only. The invention is not limited to these embodiments. Theswitch module 2802 and its operation in the FM, PM, and “I/Q” modeembodiments is substantially the same as its operation in the AM modeembodiment, described in sections 3.3.7-3.3.7.2 below.

[0385] 3.3.6.1 Operational Description.

[0386] A bias signal 2806 is gated as a result of the application of amodulated oscillating signal 2804, and a signal with a harmonically richwaveform 2814 is created. The bias signal 2806 is generally a fixedvoltage. The modulated oscillating signal 2804 can be frequencymodulated, phase modulated, or any other modulation scheme orcombination thereof. In certain embodiments, such as in certainamplitude shift keying modes, the modulated oscillating signal 2804 mayalso be amplitude modulated. The modulated oscillating signal 2804 canbe a sinusoidal wave, a rectangular wave, a triangular wave, a pulse, orany other continuous and periodic waveform. In a preferred embodiment,modulated oscillating signal 2804 would be a rectangular wave. As statedabove, one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed. Again, as stated above, forease of discussion, the term “rectangular waveform” will be used torefer to waveforms that are substantially rectangular, the term “squarewave” will refer to those waveforms that are substantially square, theterm “triangular wave” will refer to those waveforms that aresubstantially triangular, and the term ”pulse” will refer to thosewaveforms that are substantially a pulse, and it is not the intent ofthe present invention that a perfect square wave, triangle wave, orpulse be generated or needed.

[0387] The signal with harmonically rich waveform 2814, hereafterreferred to as the harmonically rich signal 2814, is a continuous andperiodic waveform that is modulated substantially the same as themodulated oscillating signal 2804. That is, if the modulated oscillatingsignal 2804 is frequency modulated, the harmonically rich signal 2814will also be frequency modulated, and if the modulated oscillatingsignal 2804 is phase modulated, the harmonically rich signal 2814 willalso be phase modulated. (In one embodiment, the harmonically richsignal 2814 is a substantially rectangular waveform.) As stated before,a continuous and periodic waveform, such as a rectangular wave, hassinusoidal components (harmonics) at frequencies that are integermultiples of the fundamental frequency of the underlying waveform (theFourier component frequencies). Thus, the harmonically rich signal 2814is composed of sinusoidal signals at frequencies that are integermultiples of the fundamental frequency of itself.

[0388] 3.3.6.2 Structural Description.

[0389] The switch module 2802 of an embodiment of the present inventionis comprised of a first input 2808, a second input 2810, a control input2820, an output 2822, and a switch 2816. A bias signal 2806 is appliedto the first input 2808 of the switch module 2802. Generally, the biassignal 2806 is a fixed voltage, and in one embodiment of the invention,a resistor 2824 is located between the bias signal 2806 and the switch2816. The second input 2810 of the switch module 2802 is generally atelectrical ground 2812. However, one skilled in the relevant art(s) willrecognize that alternative embodiments exist wherein the second input2810 may not be at electrical ground 2812, but rather a second signal2818, provided that the second signal 2818 is different than the biassignal 2806.

[0390] A modulated oscillating signal 2804 is connected to the controlinput 2820 of the switch module 2802. The modulated oscillating signal2804 may be frequency modulated or phase modulated. (In somecircumstances and embodiments, it may be amplitude modulated, such as inon/off keying, but this is not the general case, and will not bedescribed herein.) The modulated oscillating signal 2804 can be asinusoidal wave, a rectangular wave, a triangular wave, a pulse, or anyother continuous and periodic waveform. In a preferred embodiment, itwould be a rectangular wave. The modulated oscillating signal 2804causes the switch 2816 to close and open.

[0391] The harmonically rich signal 2814 described in section 3.3.6.1above, is found at the output 2822 of the switch module 2802. Theharmonically rich signal 2814 is a continuous and periodic waveform thatis modulated substantially the same as the modulated oscillating signal2804. That is, if the modulated oscillating signal 2804 is frequencymodulated, the harmonically rich signal 2814 will also be frequencymodulated, and if the modulated oscillating signal 2804 is phasemodulated, the harmonically rich signal 2814 will also be phasemodulated. In one embodiment, the harmonically rich signal 2814 has asubstantially rectangular waveform. As stated before, a continuous andperiodic waveform, such as a rectangular wave, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, the harmonically rich signal 2814 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself. Each of these sinusoidal signals isalso modulated substantially the same as the continuous and periodicwaveform (i.e., the modulated oscillating signal 2804) from which it isderived.

[0392] The switch module 2802 operates as follows. When the switch 2816is “open,” the output 2822 of switch module 2802 is at substantially thesame voltage level as bias signal 2806. Thus, since the harmonicallyrich signal 2814 is connected directly to the output 2822 of switchmodule 2802, the amplitude of harmonically rich signal 2814 is equal tothe amplitude of the bias signal 2806. When the modulated oscillatingsignal 2804 causes the switch 2816 to become “closed,” the output 2822of switch module 2802 becomes connected electrically to the second input2810 of switch module 2802 (e.g., ground 2812 in one embodiment of theinvention), and the amplitude of the harmonically rich signal 2814becomes equal to the potential present at the second input 2810 (e.g.,zero volts for the embodiment wherein the second input 2810 is connectedto electrical ground 2812). When the modulated oscillating signal 2804causes the switch 2816 to again become “open,” the amplitude of theharmonically rich signal 2814 again becomes equal to the bias signal2806. Thus, the amplitude of the harmonically rich signal 2814 is ateither of two signal levels, i.e., bias signal 2806 or ground 2812, andhas a frequency that is substantially equal to the frequency of themodulated oscillating signal 2804 that causes the switch 2816 to openand close. The harmonically rich signal 2814 is modulated substantiallythe same as the modulated oscillating signal 2804. One skilled in therelevant art(s) will recognize that any one of a number of switchdesigns will fulfill the scope and spirit of the present invention asdescribed herein.

[0393] In an embodiment of the invention, the switch 2816 is asemiconductor device, such as a diode ring. In another embodiment, theswitch is a transistor, such as a field effect transistor (FET). In anembodiment wherein the FET is gallium arsenide (GaAs), switch module2802 can be designed as seen in FIGS. 29A-29C, where the modulatedoscillating signal 2804 is connected to the gate 2902 of the GaAsFET2901, the bias signal 2806 is connected through a bias resistor 2824 tothe source 2904 of the GaAsFET 2901, and electrical ground 2812 isconnected to the drain 2906 of GaAsFET 2901. (In an alternate embodimentshown in FIG. 29C, a second signal 2818 may be connected to the drain2906 of GaAsFET 2901.) Since the drain and the source of GaAsFETs areinterchangeable, the bias signal 2806 can be applied to either thesource 2904 or to the drain 2906. If there is concern that there mightbe some source-drain asymmetry in the GaAsFET, the switch module can bedesigned as shown in FIGS. 30A-30C, wherein two GaAsFETs 3002 and 3004are connected together, with the source 3010 of the first 3002 connectedto the drain 3012 of the second 3004, and the drain 3006 of the first3002 being connected to the source 3008 of the second 3004. This designarrangement will balance substantially all asymmetries. Other switchdesigns and implementations will be apparent to persons skilled in therelevant art(s).

[0394] The output 2822 of the switch module 2802, i.e., the harmonicallyrich signal 2814, can be routed to a filter 3504 in the FM and PM modesor to a Summer 3402 in the “I/Q” mode.

[0395] 3.3.7 The Switch Module (AM Mode).

[0396] As discussed above, the amplitude modulation (AM) mode embodimentof the invention uses a switching assembly referred to as switch module3102 (FIGS. 31A-31C). As an example, switch module 3102 is a componentin switch module 1614 of FIG. 16. The invention supports numerousembodiments of the switch module. Exemplary embodiments of the switchmodule 3102 are described below. However, it should be understood thatthese examples are provided for illustrative purposes only. Theinvention is not limited to these embodiments. The switch module 3102and its operation in the AM mode embodiment is substantially the same asits operation in the FM, PM, and “I/Q” mode embodiments described insections 3.3.6-3.3.6.2 above.

[0397] 3.7.1 Operational Description.

[0398] A reference signal 3106 is gated as a result of the applicationof an oscillating signal 3104, and a signal with a harmonically richwaveform 3114 is created. The reference signal 3106 is a function of theinformation signal 2702 and may, for example, be either the summation ofthe information signal 2702 with a bias signal 2704 or it may be theinformation signal 2702 by itself. In the AM mode, the oscillatingsignal 3104 is generally not modulated, but can be.

[0399] The oscillating signal 3104 can be a sinusoidal wave, arectangular wave, a triangular wave, a pulse, or any other continuousand periodic waveform. In a preferred embodiment, it would be arectangular wave. As stated above, one skilled in the relevant art(s)will recognize the physical limitations to and mathematical obstaclesagainst achieving exact or perfect waveforms and it is not the intent ofthe present invention that a perfect waveform be generated or needed.Again, as stated above, for ease of discussion, the term “rectangularwaveform” will be used to refer to waveforms that are substantiallyrectangular, the term “square wave” will refer to those waveforms thatare substantially square, the term “triangular wave” will refer to thosewaveforms that are substantially triangular, and the term “pulse” willrefer to those waveforms that are substantially a pulse, and it is notthe intent of the present invention that a perfect square wave, trianglewave, or pulse be generated or needed.

[0400] The signal with a harmonically rich waveform 3114, hereafterreferred to as the harmonically rich signal 3114, is a continuous andperiodic waveform whose amplitude is a function of the reference signal.That is, it is an AM signal. In one embodiment, the harmonically richsignal 3114 has a substantially rectangular waveform. As stated before,a continuous and periodic waveform, such as a rectangular wave, willhave sinusoidal components (harmonics) at frequencies that are integermultiples of the fundamental frequency of the underlying waveform (theFourier component frequencies). Thus, harmonically rich signal 3114 iscomposed of sinusoidal signals at frequencies that are integer multiplesof the fundamental frequency of itself.

[0401] Those skilled in the relevant art(s) will recognize thatalternative embodiments exist wherein combinations of modulations (e.g.,PM and ASK, FM and AM, etc.) may be employed simultaneously. In thesealternate embodiments, the oscillating signal 3104 may be modulated.These alternate embodiments will be apparent to persons skilled in therelevant art(s), and thus will not be described herein.

[0402] 3.3.7.2 Structural Description.

[0403] The switch module 3102 of the present invention is comprised of afirst input 3108, a second input 3110, a control input 3120, an output3122, and a switch 3116. A reference signal 3106 is applied to the firstinput 3108 of the switch module 3102. Generally, the reference signal3106 is a function of the information signal 2702, and may either be thesummation of the information signal 2702 with a bias signal or it may bethe information signal 2702 by itself. In one embodiment of theinvention, a resistor 3124 is located between the reference signal 3106and the switch 3116. The second input 3110 of the switch module 3102 isgenerally at electrical ground 3112, however, one skilled in therelevant art(s) will recognize that alternative embodiments existwherein the second input 3110 may not be at electrical ground 3112, butrather connected to a second signal 3118. In an alternate embodiment,the inverted value of the reference signal 3106 is connected to thesecond input 3110 of the switch module 3102.

[0404] An oscillating signal 3104 is connected to the control input 3120of the switch module 3102. Generally, in the AM mode, the oscillatingsignal 3104 is not modulated, but a person skilled in the relevantart(s) will recognize that there are embodiments wherein the oscillatingsignal 3104 may be frequency modulated or phase modulated, but thesewill not be described herein. The oscillating signal 3104 can be asinusoidal wave, a rectangular wave, a triangular wave, a pulse, or anyother continuous and periodic waveform. In a preferred embodiment, itwould be a rectangular wave. The oscillating signal 3104 causes theswitch 3116 to close and open.

[0405] The harmonically rich signal 3114 described in section 3.3.7.1above is found at the output 3122 of the switch module 3102. Theharmonically rich signal 3114 is a continuous and periodic waveformwhose amplitude is a function of the amplitude of the reference signal.In one embodiment, the harmonically rich signal 3114 has a substantiallyrectangular waveform. As stated before, a continuous and periodicwaveform, such as a rectangular wave, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, harmonically rich signal 3114 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself. As previously described, the relativeamplitude of the harmonics of a continuous periodic waveform isgenerally a function of the ratio of the pulse width of the rectangularwave and the period of the fundamental frequency, and can be determinedby doing a Fourier analysis of the periodic waveform. When the amplitudeof the periodic waveform varies, as in the AM mode of the invention, thechange in amplitude of the periodic waveform has a proportional effecton the absolute amplitude of the harmonics. In other words, the AM isembedded on top of each of the harmonics.

[0406] The description of the switch module 3102 is substantially asfollows: When the switch 3116 is “open,” the amplitude of theharmonically rich signal 3114 is substantially equal to the referencesignal 3106. When the oscillating signal 3104 causes the switch 3116 tobecome “closed,” the output 3122 of the switch module 3102 becomesconnected electrically to the second input 3110 of the switch module3102 (e.g., ground 3112 in one embodiment), and the amplitude of theharmonically rich signal 3114 becomes equal to the value of the secondinput 3110 (e.g., zero volts for the embodiment wherein the second input3110 is connected to electrical ground 3112). When the oscillatingsignal 3104 causes the switch 3116 to again become “open,” the amplitudeof the harmonically rich signal 3114 again becomes substantially equalto the reference signal 3106. Thus, the amplitude of the harmonicallyrich signal 3114 is at either of two signal levels, i.e., referencesignal 3106 or ground 3112, and has a frequency that is substantiallyequal to the frequency of the oscillating signal 3104 that causes theswitch 3116 to open and close. In an alternate embodiment wherein thesecond input 3110 is connected to the second signal 3118, theharmonically rich signal 3114 varies between the reference signal 3106and the second signal 3118. One skilled in the relevant art(s) willrecognize that any one of a number of switch module designs will fulfillthe scope and spirit of the present invention.

[0407] In an embodiment of the invention, the switch 3116 is asemiconductor device, such as a diode ring. In another embodiment, theswitch is a transistor, such as, but not limited to, a field effecttransistor (FET). In an embodiment wherein the FET is gallium arsenide(GaAs), the module can be designed as seen in FIGS. 32A-32C, where theoscillating signal 3104 is connected to the gate 3202 of the GaAsFET3201, the reference signal 3106 is connected to the source 3204, andelectrical ground 3112 is connected to the drain 3206 (in the embodimentwhere ground 3112 is selected as the value of the second input 3110 ofthe switch module 3102). Since the drain and the source of GaAsFETs areinterchangeable, the reference signal 3106 can be applied to either thesource 3204 or to the drain 3206. If there is concern that there mightbe some source-drain asymmetry in the GaAsFET 3201, the switch 3116 canbe designed as shown in FIGS. 33A-33C, wherein two GaAsFETs 3302 and3304 are connected together, with the source 3310 of the first 3302connected to the drain 3312 of the second 3304, and the drain 3306 ofthe first 3302 being connected to the source 3308 of the second 3304.This design arrangement will substantially balance all asymmetries.Other switch designs and implementations will be apparent to personsskilled in the relevant art(s).

[0408] The output 3122 of the switch module 3102, i.e., the harmonicallyrich signal 3114, can be routed to a filter 3504 in the AM mode.

[0409] 3.3.8 The Summer(“I/Q” Mode).

[0410] As discussed above, the in-phase/quadrature-phase modulation(“I/Q”) mode embodiment of the invention uses a summer. See, as anexample, summer 1832 in FIG. 18. The invention supports numerousembodiments of the summer. Exemplary embodiments of the summer 3402(FIG. 34) are described below. However, it should be understood thatthese examples are provided for illustrative purposes only. Theinvention is not limited to these embodiments.

[0411] 3.3.8.1 Operational Description.

[0412] An “I” modulated signal 3404 and a “Q” modulated signal 3406 arecombined and an “I/Q” modulated signal 3408 is generated. Generally,both “I” and “Q” modulated signals 3404 and 3406 are harmonically richwaveforms, which are referred to as the harmonically rich “I” signal3404 and the harmonically rich “Q” signal 3406. Similarly, “I/Q”modulated signal 3408 is harmonically rich and is referred to as theharmonically rich “I/Q” signal. In one embodiment, these harmonicallyrich signals have substantially rectangular waveforms. As stated above,one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed.

[0413] In a typical embodiment, the harmonically rich “I” signal 3404and the harmonically rich “Q” signal 3406 are phase modulated, as is theharmonically rich “I/Q” signal 3408. A person skilled in the relevantart(s) will recognize that other modulation techniques, such asamplitude modulating the “I/Q” signal, may also be used in the “I/Q”mode without deviating from the scope and spirit of the invention.

[0414] As stated before, a continuous and periodic waveform, such asharmonically rich “I/Q” signal 3408, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, harmonically rich “I/Q” signal 3408 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself. These sinusoidal signals are alsomodulated substantially the same as the continuous and periodic waveformfrom which they are derived. That is, in this embodiment, the sinusoidalsignals are phase modulated, and include the information from both the“I” modulated signal and the “Q” modulated signal.

[0415] 3.3.8.2 Structural Description.

[0416] The design and use of a summer 3402 is well known to thoseskilled in the relevant art(s). A summer 3402 may be designed andfabricated from discrete components, or it may be purchased “off theshelf.” A summer 3402 accepts a harmonically rich “I” signal 3404 and aharmonically rich “Q” signal 3406, and combines them to create aharmonically rich “I/Q” signal 3408. In a preferred embodiment of theinvention, the harmonically rich “I” signal 3404 and the harmonicallyrich “Q” signal 3406 are both phase modulated. When the harmonicallyrich “I” signal 3404 and the harmonically rich “Q” signal 3406 are bothphase modulated, the harmonically rich “I/Q” signal 3408 is also phasemodulated.

[0417] As stated before, a continuous and periodic waveform, such as theharmonically rich “I/Q” signal 3408, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, the harmonically rich “I/Q” signal 3408 is composedof “I/Q” sinusoidal signals at frequencies that are integer multiples ofthe fundamental frequency of itself. These “I/Q” sinusoidal signals arealso phase modulated substantially the same as the continuous andperiodic waveform from which they are derived (i.e., the harmonicallyrich “I/Q” signal 3408).

[0418] The output of the summer 3402 is then routed to a filter 3504.

[0419] 3.3.9 The Filter (FM, PM, AM, and “I/Q” Modes).

[0420] As discussed above, all modulation mode embodiments of theinvention use a filter. See, as an example, filter 1218 in FIG. 12,filter 1414 in FIG. 14, filter 1618 in FIG. 16, and filter 1836 in FIG.18. The invention supports numerous embodiments of the filter. Exemplaryembodiments of the filter 3504 (FIG. 35) are described below. However,it should be understood that these examples are provided forillustrative purposes only. The invention is not limited to theseembodiments.

[0421] 3.3.9.1 Operational Description.

[0422] A modulated signal with a harmonically rich waveform 3502 isaccepted. It is referred to as the harmonically rich signal 3502. Asstated above, a continuous and periodic waveform, such as theharmonically rich signal 3502, is comprised of sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform from which they are derived. Theseare called the Fourier component frequencies. In one embodiment of theinvention, the undesired harmonic frequencies are removed, and thedesired frequency 3506 is output. In an alternate embodiment, aplurality of harmonic frequencies are output.

[0423] The harmonic components of the harmonically rich signal 3502 aremodulated in the same manner as the harmonically rich signal 3502itself. That is, if the harmonically rich signal 3502 is frequencymodulated, all of the harmonic components of that signal are alsofrequency modulated. The same is true for phase modulation, amplitudemodulation, and “I/Q” modulation.

[0424] 3.3.9.2 Structural Description.

[0425] The design and use of a filter 3504 is well known to thoseskilled in the relevant art(s). A filter 3504 may be designed andfabricated from discrete components or it may be purchased “off theshelf.” The filter 3504 accepts the harmonically rich signal 3502 fromthe switch module 2802 or 3102 in the FM, PM, and AM modes, and from thesummer 3402 in the “I/Q” mode. The harmonically rich signal 3502 is acontinuous and periodic waveform. As such, it is comprised of sinusoidalcomponents (harmonics) that are at frequencies that are integermultiples of the fundamental frequency of the underlying harmonicallyrich signal 3502. The filter 3504 removes those sinusoidal signalshaving undesired frequencies. The signal 3506 that remains is at thedesired frequency, and is called the desired output signal 3506.

[0426] To achieve this result, according to an embodiment of theinvention, a filter 3504 is required to filter out the unwantedharmonics of the harmonically rich signal 3502.

[0427] The term “Q” is used to represent the ratio of the centerfrequency of the desired output signal 3506 to the half power bandwidth. Looking at FIG. 36 we see a desired frequency 3602 of 900 MHz.The filter 3504 is used to ensure that only the energy at that frequency3602 is transmitted. Thus, the bandwidth 3604 at half power (theso-called “3 dB down” point) should be as narrow as possible. The ratioof frequency 3602 to bandwidth 3604 is defined as “Q.” As shown on FIG.36, if the “3 dB down” point is at plus or minus 15 MHz, the value of Qwill be 900÷(15+15) or 30. With the proper selection of elements for anyparticular frequency, Qs on the order of 20 or 30 are achievable.

[0428] For crisp broadcast frequencies, it is desired that Q be as highas possible and practical, based on the given application andenvironment. The purpose of the filter 3504 is to filter out theunwanted harmonics of the harmonically rich signal. The circuits aretuned to eliminate all other harmonics except for the desired frequency3506 (e.g., the 900 MHz harmonic 3602). Turning now to FIGS. 37A and37B, we see examples of filter circuits. One skilled in the relevantart(s) will recognize that a number of filter designs will accomplishthe desired goal of passing the desired frequency while filtering theundesired frequencies.

[0429]FIG. 37A illustrates a circuit having a capacitor in parallel withan inductor and shunted to ground. In FIG. 37B, a capacitor is in serieswith an inductor, and a parallel circuit similar to that in FIG. 37A isconnected between the capacitor and inductor and shunted to ground.

[0430] The modulated signal at the desired frequency 3506 may then berouted to the transmission module 3804.

[0431] 3.3.10 The Transmission Module (FM, PM, AM, and “I/Q” Modes).

[0432] As discussed above, the modulation mode embodiments of theinvention preferably use a transmission module. See, as an example,transmission module 1222 in FIG. 12, transmission module 1418 in FIG.14, transmission module 1622 in FIG. 16, and transmission module 1840 inFIG. 18. The transmission module is optional, and other embodiments maynot include a transmission module. The invention supports numerousembodiments of the transmission module. Exemplary embodiments of thetransmission module 3804 (FIG. 38) are described below. However, itshould be understood that these examples are provided for illustrativepurposes only. The invention is not limited to these embodiments.

[0433] 3.3.10.1 Operational Description.

[0434] A modulated signal at the desired frequency 3802 is accepted andis transmitted over the desired medium, such as, but not limited to,over-the-air broadcast or point-to-point cable.

[0435] 3.3.10.2 Structural Description.

[0436] The transmission module 3804 receives the signal at the desiredEM frequency 3802. If it is intended to be broadcast over the air, thesignal may be routed through an optional antenna interface and then tothe antenna for broadcast. If it is intended for the signal to betransmitted over a cable from one point to another, the signal may berouted to an optional line driver and out through the cable. One skilledin the relevant art(s) will recognize that other transmission media maybe used.

[0437] 3.3.11 Other Implementations.

[0438] The implementations described above are provided for purposes ofillustration. These implementations are not intended to limit theinvention. Other implementation embodiments are possible and covered bythe invention, such as but not limited to software, software/hardware,and firmware implementations of the systems and components of theinvention. Alternate implementations and embodiments, differing slightlyor substantially from those described herein, will be apparent topersons skilled in the relevant art(s) based on the teachings containedherein. Such alternate implementations fall within the scope and spiritof the present invention.

[0439] 4. Harmonic Enhancement.

[0440] 4.1 High Level Description.

[0441] This section (including its subsections) provides a high-leveldescription of harmonic enhancement according to the present invention.In particular, pulse shaping is described at a high-level. Also, astructural implementation for achieving this process is described at ahigh-level. This structural implementation is described herein forillustrative purposes, and is not limiting. In particular, the processdescribed in this section can be achieved using any number of structuralimplementations, one of which is described in this section. The detailsof such structural implementations will be apparent to persons skilledin the relevant art(s) based on the teachings contained herein.

[0442] It is noted that some embodiments of the invention includeharmonic enhancement, whereas other embodiments do not.

[0443] 4.1.1 Operational Description.

[0444] To better understand the generation and extraction of harmonics,and the purpose behind shaping the waveforms to enhance the harmonics,the following discussion of Fourier analysis as it applies to thepresent invention is offered.

[0445] A discovery made by Baron Jean B. J. Fourier (1768-1830) showedthat continuous and periodic waveforms are comprised of a plurality ofsinusoidal components, called harmonics. More importantly, the frequencyof these components are integer multiples of the frequency of theoriginal waveform (called the fundamental frequency). The amplitude ofeach of these component waveforms depends on the shape of the originalwaveform. The derivations and proofs of Baron Fourier's analysis arewell known to those skilled in the relevant art(s).

[0446] The most basic waveform which is continuous and periodic is asine wave. It has but one harmonic, which is at the fundamentalfrequency. This is also called the first harmonic. Since it only has onecomponent, the amplitude of the harmonic component is equal to theamplitude of the original waveform, i.e., the sine wave itself. The sinewave is not considered to be “harmonically rich.”

[0447] An impulse train is the other extreme case of a periodicwaveform. Mathematically, it is considered to have zero width. Themathematical analysis in this case shows that there are harmonics at allmultiples of the frequency of the impulse. That is, if the impulse has afrequency of F_(i), then the harmonics are sinusoidal waves at 1·F_(i),2·F_(i), 3·F_(i), 4·F_(i), etc. As the analysis also shows in thisparticular case, the amplitude of all of the harmonics are equal. Thisis indeed, a “harmonically rich” waveform, but is realisticallyimpractical with current technology.

[0448] A more typical waveform is a rectangular wave, which is a seriesof pulses. Each pulse will have a width (called a pulse width, or “τ”),and the series of pulses in the waveform will have a period (“T” whichis the inverse of the frequency, i.e., T=1/F_(r), where “F_(r)” is thefundamental frequency of the rectangular wave). One form of rectangularwave is the square wave, where the signal is at a first state (e.g.,high) for the same amount of time that it is at the second state (e.g.,low). That is, the ratio of the pulse width to period (τ/T) is 0.5.Other forms of rectangular waves, other than square waves, are typicallyreferred to simply as “pulses,” and have τ/T<0.5 (i.e., the signal willbe “high” for a shorter time than it is “low”). The mathematicalanalysis shows that there are harmonics at all of the multiples of thefundamental frequency of the signal. Thus, if the frequency of therectangular waveform is F_(r), then the frequency of the first harmonicis 1·F_(r), the frequency of the second harmonic is 2·F_(r), thefrequency of the third harmonic is 3·F_(r), and so on. There are someharmonics for which the amplitude is zero. In the case of a square wave,for example, the “null points” are the even harmonics. For other valuesof τ/T, the “null points” can be determined from the mathematicalequations. The general equation for the amplitude of the harmonics in arectangular wave having an amplitude of A_(pulse) is as follows:

Amplitude(n^(th) harmonic)=A _(n) ={[A _(pulse)][(2/π)/n] sin[n·π·(τ/T)]}  Eq. 1

[0449] Table 6000 of FIG. 60 shows the amplitudes of the first fiftyharmonics for rectangular waves having six different τ/T ratios. The τ/Tratios are 0.5 (a square wave), 0.25, 0.10, 0.05, 0.01, and 0.005. (Oneskilled in the relevant art(s) will recognize that A_(pulse) is set tounity for mathematical comparison.) From this limited example, it can beseen that the ratio of pulse width to period is a significant factor indetermining the relative amplitudes of the harmonics. Notice too, thatfor the case where τ/T=0.5 (i.e., a square wave), the relationshipstated above (i.e., only odd harmonics are present) holds. Note that asτ/T becomes small (i.e., the pulse approaches an impulse), theamplitudes of the harmonics becomes substantially “flat.” That is, thereis very little decrease in the relative amplitudes of the harmonics. Oneskilled in the relevant art(s) will understand how to select the desiredpulse width for any given application based on the teachings containedherein. It can also be shown mathematically and experimentally that if asignal with a continuous and periodic waveform is modulated, thatmodulation is also present on every harmonic of the original waveform.

[0450] From the foregoing, it can be seen how pulse width is animportant factor in assuring that the harmonic waveform at the desiredoutput frequency has sufficient amplitude to be useful without requiringelaborate filtering or unnecessary amplification.

[0451] Another factor in assuring that the desired harmonic hassufficient amplitude is how the switch 2816 and 3116 (FIGS. 28A and 31A)in the switch module 2802 and 3102 responds to the control signal thatcauses the switch to close and to open (i.e., the modulated oscillatingsignal 2804 of FIG. 28 and the oscillating signal 3104 of FIG. 31). Ingeneral, switches have two thresholds. In the case of a switch that isnormally open, the first threshold is the voltage required to cause theswitch to close. The second threshold is the voltage level at which theswitch will again open. The convention used herein for ease ofillustration and discussion (and not meant to be limiting) is for thecase where the switch is closed when the control signal is high, andopen when the control signal is low. It would be apparent to one skilledin the relevant art(s) that the inverse could also be used. Typically,these voltages are not identical, but they may be. Another factor is howrapidly the switch responds to the control input once the thresholdvoltage has been applied. The objective is for the switch to close andopen such that the bias/reference signal is “crisply” gated. That is,preferably, the impedance through the switch must change from a highimpedance (an open switch) to a low impedance (a closed switch) and backagain in a very short time so that the output signal is substantiallyrectangular.

[0452] It is an objective of this invention in the transmitterembodiment that the intelligence in the information signal is to betransmitted. That is, the information is modulated onto the transmittedsignal. In the FM and PM modes, to achieve this objective, theinformation signal is used to modulate the oscillating signal 2804. Theoscillating signal 2804 then causes the switch 2816 to close and open.The information that is modulated onto the oscillating signal 2804 mustbe faithfully reproduced onto the signal that is output from the switchcircuit (i.e., the harmonically rich signal 2814). For this to occurefficiently, in embodiments of the invention, the switch 2816 preferablycloses and opens crisply so that the harmonically rich signal 2814changes rapidly from the bias/reference signal 2806 (or 3106) to ground2812 (or the second signal level 2818 in the alternate embodiment). Thisrapid rise and fall time is desired so that the harmonically rich signal2814 will be “harmonically rich.” (In the case of AM, the oscillatingsignal 3104 is not modulated, but the requirement for “crispness” stillapplies.)

[0453] For the switch 2816 to close and open crisply, the oscillatingsignal 2804 must also be crisp. If the oscillating signal 2804 issinusoidal, the switch 2816 will open and close when the thresholdvoltages are reached, but the pulse width of the harmonically richsignal 2814 may not be as small as is needed to ensure the amplitude ofthe desired harmonic of the harmonically rich signal 2814 issufficiently high to allow transmission without elaborate filtering orunnecessary amplification. Also, in the embodiment wherein the switch2816 is a GaAsFET 2901, if the oscillating signal 2804 that is connectedto the gate 2902 of the GaAsFET 2901 (i.e., the signal that causes theswitch 2816 to close and open) is a sinusoidal wave, the GaAsFET 2901will not crisply close and open, but will act more like an amplifierthan a switch. (That is, it will conduct during the time that theoscillating signal is rising and falling below the threshold voltages,but will not be a “short.”) In order to make use of the benefits of aGaAsFET's capability to close and open at high frequencies, theoscillating signal 2804 connected to the gate 2902 preferably has arapid rise and fall time. That is, it is preferably a rectangularwaveform, and preferably has a pulse width to period ratio the same asthe pulse width to period ratio of the harmonically rich signal 2814.

[0454] As stated above, if a signal with a continuous and periodicwaveform is modulated, that modulation occurs on every harmonic of theoriginal waveform. Thus, in the FM and PM modes, when the information ismodulated onto the oscillating signal 2804 and the oscillating signal2804 is used to cause the switch 2816 to close and open, the resultingharmonically rich signal 2814 that is output from the switch module 2802will also be modulated. If the oscillating signal 2804 is crisp, theswitch 2816 will close and open crisply, the harmonically rich signal2814 will be harmonically rich, and each of the harmonics of theharmonically rich signal 2814 will have the information modulated on it.

[0455] Because it is desired that the oscillating signal 2804 be crisp,harmonic enhancement may be needed in some embodiments. Harmonicenhancement may also be called “pulse shaping” since the purpose is toshape the oscillating signal 2804 into a string of pulses of a desiredpulse width. If the oscillating signal is sinusoidal, harmonicenhancement will shape the sinusoidal signal into a rectangular (orsubstantially rectangular) waveform with the desired pulse width toperiod ratio. If the oscillating signal 2804 is already a square wave ora pulse, harmonic enhancement will shape it to achieve the desired ratioof pulse width to period. This will ensure an efficient transfer of themodulated information through the switch.

[0456] Three exemplary embodiments of harmonic enhancement are describedbelow for illustrative purposes. However, the invention is not limitedto these embodiments. Other embodiments will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.

[0457] 4.1.2 Structural Description.

[0458] The shape of the oscillating signal 2804 causes the switch 2816to close and open. The shape of the oscillating signal 2804 and theselection of the switch 2816 will determine how quickly the switch 2816closes and opens, and how long it stays closed compared to how long itstays open. This then will determine the “crispness” of the harmonicallyrich signal 2814. (That is, whether the harmonically rich signal 2814 issubstantially rectangular, trapezoidal, triangular, etc.) As shownabove, in order to ensure that the desired harmonic has the desiredamplitude, the shape of the oscillating signal 2804 should besubstantially optimized.

[0459] The harmonic enhancement module (HEM) 4602 (FIG. 46) is alsoreferred to as a “pulse shaper.” It “shapes” the oscillating signals2804 and 3104 that drive the switch modules 2802 and 3102 described insections 3.3.6-3.3.6.2 and 3.3.7-3.3.7.2. Harmonic enhancement module4602 preferably transforms a continuous and periodic waveform 4604 intoa string of pulses 4606. The string of pulses 4606 will have a period,“T,” determined by both the frequency of the continuous and periodicwaveform 4604 and the design of the pulse shaping circuit within theharmonic enhancement module 4602. Also, each pulse will have a pulsewidth, “τ,” determined by the design of the pulse shaping circuit. Theperiod of the pulse stream, “T,” determines the frequency of the switchclosing (the frequency being the inverse of the period), and the pulsewidth of the pulses, “τ,” determines how long the switch stays closed.

[0460] In the embodiment described above in sections 3.3.6-3.3.6.2 (and3.3.7-3.3.7.2), when the switch 2816 (or 3116) is open, the harmonicallyrich signal 2814 (or 3114) will have an amplitude substantially equal tothe bias signal 2806 (or reference signal 3106). When the switch 2816(or 3116) is closed, the harmonically rich signal 2814 (or 3114) willhave an amplitude substantially equal to the potential of signal 2812 or2818 (or 3112 or 3118) of the second input 2810 (or 3110) of the switchmodule 2802 (or 3102). Thus, for the case where the oscillating signal2804 (or 3104) driving the switch module 2802 (or 3102) is substantiallyrectangular, the harmonically rich signal 2814 (or 3114) will havesubstantially the same frequency and pulse width as the shapedoscillating signal 2804 (or 3104) that drives the switch module 2802 (or3102). This is true for those cases wherein the oscillating signal 2804(or 3104) is a rectangular wave.

[0461] One skilled in the relevant art(s) will understand that the term“rectangular wave” can refer to all waveforms that are substantiallyrectangular, including square waves and pulses.

[0462] The purpose of shaping the signal is to control the amount oftime that the switch 2816 (or 3116) is closed. As stated above, theharmonically rich signal 2814 (or 3114) has a substantially rectangularwaveform. Controlling the ratio of the pulse width of the harmonicallyrich signal 2814 (or 3114) to its period will result in the shape of theharmonically rich signal 2814 (or 3114) being substantially optimized sothat the relative amplitudes of the harmonics are such that the desiredharmonic can be extracted without unnecessary and elaborateamplification and filtering.

[0463] 4.2 Exemplary Embodiments.

[0464] Various embodiments related to the method(s) and structure(s)described above are presented in this section (and its subsections).These embodiments are described herein for purposes of illustration, andnot limitation. The invention is not limited to these embodiments.Alternate embodiments (including equivalents, extensions, variations,deviations, etc., of the embodiments described herein) will be apparentto persons skilled in the relevant art(s) based on the teachingscontained herein. The invention is intended and adapted to include suchalternate embodiments.

[0465] 4.2.1 First Embodiment: When a Square Wave Feeds the HarmonicEnhancement Module to Create One Pulse Per Cycle.

[0466] 4.2.1.1 Operational Description.

[0467] According to this embodiment, a continuous periodic waveform 4604is received and a string of pulses 4606 is output. The continuousperiodic waveform 4604 may be a square wave or any other continuousperiodic waveform that varies from a value recognized as a “digital low”to a value recognized as a “digital high.” One pulse is generated percycle of the continuous and periodic waveform 4604. The descriptiongiven herein will be for the continuous periodic waveform 4604 that is asquare wave, but one skilled in the relevant art(s) will appreciate thatother waveforms may also be “shaped” into waveform 4606 by thisembodiment.

[0468] 4.2.1.2 Structural Description.

[0469] In this first embodiment of a harmonic enhancement module 4602,herein after referred to as a pulse shaping circuit 4602, a continuousperiodic waveform 4604 that is a square wave is received by the pulseshaping circuit 4602. The pulse shaping circuit 4602 is preferablycomprised of digital logic devices that result in a string of pulses4606 being output that has one pulse for every pulse in the continuousperiodic waveform 4604, and preferably has a τ/T ratio less than 0.5.

[0470] 4.2.2 Second Embodiment: When a Square Wave Feeds the HarmonicEnhancement Module to Create Two Pulses Per Cycle.

[0471] 4.2.2.1 Operational Description.

[0472] In this embodiment, a continuous periodic waveform 4604 isreceived and a string of pulses 4606 is output. In this embodiment,there are two pulses output for every period of the continuous periodicwaveform 4604. The continuous periodic waveform 4604 may be a squarewave or any other continuous periodic waveform that varies from a valuerecognized as a “digital low” to a value recognized as a “digital high.”The description given herein will be for a continuous periodic waveform4604 that is a square wave, but one skilled in the relevant art(s) willappreciate that other waveforms may also be “shaped” into waveform 4606by this embodiment.

[0473] 4.2.2.2 Structural Description.

[0474] In this second embodiment of a pulse shaping circuit 4602, acontinuous periodic waveform 4604 that is a square wave is received bythe pulse shaping circuit 4602. The pulse shaping circuit 4602 ispreferably comprised of digital logic devices that result in a string ofpulses 4606 being output that has two pulses for every pulse in thecontinuous periodic waveform 4604, and preferably has a τ/T ratio lessthan 0.5.

[0475] 4.2.3 Third Embodiment: When Any Waveform Feeds the Module.

[0476] 4.2.3.1 Operational Description.

[0477] In this embodiment, a continuous periodic waveform 4604 of anyshape is received and a string of pulses 4606 is output.

[0478] 4.2.3.2 Structural Description.

[0479] In this third embodiment of a pulse shaping circuit 4602, acontinuous periodic waveform 4604 of any shape is received by the pulseshaping circuit 4602. The pulse shaping circuit 4602 is preferablycomprised of a series of stages, each stage shaping the waveform untilit is substantially a string of pulses 4606 with preferably a τ/T ratioless than 0.5.

[0480] 4.2.4 Other Embodiments.

[0481] The embodiments described above are provided for purposes ofillustration. These embodiments are not intended to limit the invention.Alternate embodiments, differing slightly or substantially from thosedescribed herein, will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternateembodiments fall within the scope and spirit of the present invention.

[0482] 4.3 Implementation Examples.

[0483] Exemplary operational and/or structural implementations relatedto the method(s), structure(s), and/or embodiments described above arepresented in this section (and its subsections). These components andmethods are presented herein for purposes of illustration, and notlimitation. The invention is not limited to the particular examples ofcomponents and methods described herein. Alternatives (includingequivalents, extensions, variations, deviations, etc., of thosedescribed herein) will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternatives fallwithin the scope and spirit of the present invention.

[0484] 4.3.1 First Digital Logic Circuit.

[0485] An exemplary implementation of the first embodiment described insections 4.2.1-4.2.1.2 is illustrated in FIG. 39. In particular, thecircuit shown in FIG. 39A is a typical circuit design for a pulseshaping circuit 4602 using digital logic devices. Also shown in FIGS.39B-39D are representative waveforms at three nodes within the circuit.In this embodiment, pulse shaper 3900 uses an inverter 3910 and an ANDgate 3912 to produce a string of pulses. An inverter, such as inverter3910, changes the sign of the input, and an AND gate, such as AND gate3912, outputs a digital “high” when all of the input signals are digital“highs.” The input to pulse shaper 3900 is waveform 3902, and, forillustrative purposes, is shown here as a square wave. The output ofinverter 3910 is waveform 3904, which is also a square wave. However,because of the circuitry of the inverter 3910, there is a delay betweenthe application of the input and the corresponding sign change of theoutput. If waveform 3902 starts “low,” waveform 3904 will be “high”because it has been inverted by inverter 3910. When waveform 3902switches to “high,” AND gate 3912 will momentarily see two “high”signals, thus causing its output waveform 3906 to be “high.” Wheninverter 3910 has inverted its input (waveform 3902) and caused waveform3904 to become “low,” AND gate 3912 will then see only one “high”signal, and the output waveform 3906 will become “low.” Thus, the outputwaveform 3906 will be “high” for only the period of time that bothwaveforms 3902 and 3904 are high, which is the time delay of theinverter 3910. Accordingly, as is apparent from FIGS. 39B-39D, pulseshaper 3900 receives a square wave and generates a string of pulses,with one pulse generated per cycle of the square wave.

[0486] 4.3.2 Second Digital Logic Circuit.

[0487] An exemplary implementation of the second embodiment described insections 4.2.2-4.2.2.2 is illustrated in FIG. 40. In particular, thecircuit of FIG. 40A is a typical circuit design for a pulse shapingcircuit 4602 using digital logic devices. Also shown in FIGS. 40B-40Dare representative waveforms at three nodes within the circuit. In thisembodiment, pulse shaping circuit 4000 uses an inverter 4010 and anexclusive NOR (XNOR) gate 4012. An XNOR, such as XNOR 4012, outputs adigital “high” when both inputs are digital “highs” and when bothsignals are digital “lows.” Waveform 4002, which is shown here as asquare wave identical to that shown above as waveform 3902, begins inthe “low” state. Therefore, the output of inverter 4010 will begin atthe “high” state. Thus, XNOR gate 4012 will see one “high” input and one“low” input, and its output waveform 4006 will be “low.” When waveform4002 changes to “high,” XNOR gate 4012 will have two “high” inputs untilthe waveform 4004 switches to “low.” Because it sees two “high” inputs,its output waveform 4006 will be “high.”When waveform 4004 becomes“low,” XNOR gate 4012 will again see one “high” input (waveform 4002)and one “low” input (waveform 4004). When waveform 4002 switches back to“low,” XNOR gate 4012 will see two “low” inputs, and its output willbecome “high.” Following the time delay of inverter 4010, waveform 4004will change to “high,” and XNOR gate 4012 will again see one “high”input (waveform 4004) and one “low” input (waveform 4002). Thus,waveform 4006 will again switch to “low.” Accordingly, as is apparentfrom FIGS. 40B-40D, pulse shaper 4000 receives a square wave andgenerates a string of pulses, with two pulses generated per cycle of thesquare wave.

[0488] 4.3.3 Analog Circuit.

[0489] An exemplary implementation of the third embodiment described insections 4.2.3-4.2.3.2 is illustrated in FIG. 41. In particular, thecircuit shown in FIG. 41 is a typical pulse shaping circuit 4602 wherean input signal 4102 is shown as a sine wave. Input signal 4102 feedsthe first circuit element 4104, which in turn feeds the second, and soon. Typically, three circuit elements 4104 produce incrementally shapedwaveforms 4120, 4122, and 4124 before feeding a capacitor 4106. Theoutput of capacitor 4106 is shunted to ground 4110 through a resistor4108 and also feeds a fourth circuit element 4104. An output signal 4126is a pulsed output, with a frequency that is a function of the frequencyof input signal 4102.

[0490] An exemplary circuit for circuit elements 4104 is shown in FIG.43. Circuit 4104 is comprised of an input 4310, an output 4312, fourFETs 4302, two diodes 4304, and a resistor 4306. One skilled in therelevant art(s) would recognize that other pulse shaping circuit designscould also be used without deviating from the scope and spirit of theinvention.

[0491] 4.3.4 Other Implementations.

[0492] The implementations described above are provided for purposes ofillustration. These implementations are not intended to limit theinvention. Alternate implementations, differing slightly orsubstantially from those described herein, will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.Such alternate implementations fall within the scope and spirit of thepresent invention.

[0493] 5. Amplifier Module.

[0494] 5.1 High Level Description.

[0495] This section (including its subsections) provides a high-leveldescription of the amplifier module according to the present invention.In particular, amplification is described at a high-level. Also, astructural implementation for achieving signal amplification isdescribed at a high-level. This structural implementation is describedherein for illustrative purposes, and is not limiting. In particular,the process described in this section can be achieved using any numberof structural implementations, one of which is described in thissection. The details of such structural implementations will be apparentto persons skilled in the relevant art(s) based on the teachingscontained herein.

[0496] 5.1.1 Operational Description.

[0497] Even though the present invention is intended to be used withoutrequiring amplification, there may be circumstance when, in theembodiment of the present invention wherein it is being used as atransmitter, it may prove desirable to amplify the modulated signalbefore it is transmitted. In another embodiment of the invention whereinit is being used as a stable signal source for a frequency or phasecomparator, it may also be desirable to amplify the resultant signal atthe desired frequency.

[0498] The requirement may come about for a number of reasons. A firstmay be that the bias/reference signal is too low to support the desireduse. A second may be because the desired output frequency is very highrelative to the frequency of the oscillating signal that controls theswitch. A third reason may be that the shape of the harmonically richsignal is such that the amplitude of the desired harmonic is low.

[0499] In the first case, recall that the amplitude of thebias/reference signal determines the amplitude of the harmonically richsignal which is present at the output of the switch circuit. (Seesections 3.3.6-3.3.6.2 and 3.3.7-3.3.7.2.) Further recall that theamplitude of the harmonically rich signal directly impacts the amplitudeof each of the harmonics. (See the equation in section 4.1, above.)

[0500] In the second instance, if the frequency of the oscillatingsignal is relatively low compared to the desired output frequency of theup-converter, a high harmonic will be needed. As an example, if theoscillating signal is 60 MHz, and the desired output frequency is at 900MHz, the 15^(th) harmonic will be needed. In the case where τ/T is 0.1,it can be seen from Table 6000 of FIG. 60 that the amplitude of the15^(th) harmonic (A₁₅) is 0.0424, which is 21.5% of the amplitude of thefirst harmonic (A₁=0.197). There may be instances wherein this isinsufficient for the desired use, and consequently it must be amplified.

[0501] The third circumstance wherein the amplitude of the output mayneed to be amplified is when the shape of the harmonically rich signalin not “crisp” enough to provide harmonics with enough amplitude for thedesired purpose. If, for example, the harmonically rich signal issubstantially triangular, and given the example above where theoscillating signal is 60 MHz and the desired output signal is 900 MHz,the 15^(th) harmonic of the triangular wave is 0.00180. This issignificantly lower than the amplitude of the 15^(th) harmonic of the“0.1” rectangular wave (shown above to be 0.0424) and can bemathematically shown to be 0.4% of the amplitude of the 1^(st) harmonicof the triangular wave (which is 0.405). Thus, in this example, the1^(st) harmonic of the triangular wave has an amplitude that is largerthan the amplitude of the 1^(st) harmonic of the “0.1” rectangular wave,but at the 15^(th) harmonic, the triangular wave is significantly lowerthan the “0.1” rectangular wave.

[0502] Another reason that the desired harmonic may need to be amplifiedis that circuit elements such as the filter may cause attenuation in theoutput signal for which a designer may wish to compensate.

[0503] The desired output signal can be amplified in a number of ways.One is to amplify the bias/reference signal to ensure that the amplitudeof the harmonically rich wave form is high. A second is to amplify theharmonically rich waveform itself. A third is to amplify the desiredharmonic only. The examples given herein are for illustrative purposesonly and are not meant to be limiting on the present invention. Othertechniques to achieve amplification of the desired output signal wouldbe apparent to those skilled in the relevant art(s).

[0504] 5.1.2 Structural Description.

[0505] In one embodiment, a linear amplifier is used to amplify thebias/reference signal. In another embodiment, a linear amplifier is usedto amplify the harmonically rich signal. And in yet another embodiment,a linear amplifier is used to amplify the desired output signal. Otherembodiments, including the use of non-linear amplifiers, will beapparent to persons skilled in the relevant art(s).

[0506] 5.2 Exemplary Embodiment.

[0507] An embodiment related to the method(s) and structure(s) describedabove is presented in this section (and its subsections). Thisembodiment is described herein for purposes of illustration, and notlimitation. The invention is not limited to this embodiment. Alternateembodiments (including equivalents, extensions, variations, deviations,etc., of the embodiment described herein) will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.The invention is intended and adapted to include such alternateembodiments.

[0508] 5.2.1 Linear Amplifier.

[0509] The exemplary linear amplifier described herein will be directedtowards an amplifier composed of solid state electronic devices to beinserted in the circuit at one or more points. Other amplifiers suitablefor use with the invention will be apparent to persons skilled in therelevant art(s). As shown in FIG. 47, an amplifier module 4702 receivesa signal requiring amplification 4704 and outputs an amplified signal4706. It would be apparent to one skilled in the relevant art(s) that aplurality of embodiments may be employed without deviating from thescope and intent of the invention described herein.

[0510] 5.2.1.1 Operational Description.

[0511] The desired output signal can be amplified in a number of ways.Such amplification as described in the section may be in addition to thetechniques described above to enhance the shape of the harmonically richsignal by pulse shaping of the oscillating signal that causes the switchto close and open.

[0512] 5.2.1.2 Structural Description.

[0513] In one embodiment, a linear amplifier is placed between thebias/reference signal and the switch module. This will increase theamplitude of the bias/reference signal, and as a result, will raise theamplitude of the harmonically rich signal that is the output of theswitch module. This will have the effect of not only raising theamplitude of the harmonically rich signal, it will also raise theamplitude of all of the harmonics. Some potential limitation of thisembodiment are: the amplified bias/reference signal may exceed thevoltage design limit for the switch in the switch circuit; theharmonically rich signal coming out of the switch circuit may have anamplitude that exceeds the voltage design limits of the filter; and/orunwanted distortion may occur from having to amplify a wide bandwidthsignal.

[0514] A second embodiment employs a linear amplifier between the switchmodule and the filter. This will raise the amplitude of the harmonicallyrich signal. It will also raise the amplitude of all of the harmonics ofthat signal. In an alternate implementation of this embodiment, theamplifier is tuned so that it only amplifies the desired frequencies.Thus, it acts both as an amplifier and as a filter. A potentiallimitation of this embodiment is that when the harmonically rich signalis amplified to raise a particular harmonic to the desired level theamplitude of the whole waveform is amplified as well. For example, inthe case where the amplitude of the pulse, A_(pulse), is equal to 1.0,to raise the 15^(th) harmonic from 0.0424 volts to 0.5 volts, theamplitude of each pulse in the harmonically rich signal, A_(pulse), willincrease from 1.0 to 11.8 volts. This may well exceed the voltage designlimit of the filter.

[0515] A third embodiment of an amplifier module will place a linearamplifier between the filter and the transmission module. This will onlyraise the amplitude of the desired harmonic, rather than the entireharmonically rich signal.

[0516] Other embodiments, such as the use of non-linear amplifiers, willbe apparent to one skilled in the relevant art(s), and will not bedescribed herein.

[0517] 5.2.2 Other Embodiments.

[0518] The embodiments described above are provided for purposes ofillustration. These embodiments are not intended to limit the invention.Alternate embodiments, differing slightly or substantially from thosedescribed herein, will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternateembodiments fall within the scope and spirit of the present invention.

[0519] 5.3 Implementation Examples.

[0520] Exemplary operational and/or structural implementations relatedto the method(s), structure(s), and/or embodiments described above arepresented in this section (and its subsections). These components andmethods are presented herein for purposes of illustration, and notlimitation. The invention is not limited to the particular examples ofcomponents and methods described herein. Alternatives (includingequivalents, extensions, variations, deviations, etc., of thosedescribed herein) will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternatives fallwithin the scope and spirit of the present invention.

[0521] 5.3.1 Linear Amplifier.

[0522] Although described below as if it were placed after the filter,the amplifier may also be placed before the filter without deviatingfrom the intent of the invention

[0523] 5.3.1.1 Operational Description.

[0524] According to embodiments of the invention, a linear amplifierreceives a first signal at a first amplitude, and outputs a secondsignal at a second amplitude, wherein the second signal is proportionalto the first signal. It is a objective of an amplifier that theinformation embedded onto the first signal waveform will also beembedded onto the second signal. Typically, it is desired that there beas little distortion in the information as possible.

[0525] In a preferred embodiment, the second signal is higher inamplitude than the first signal, however, there may be implementationswherein it is desired that the second signal be lower than the firstsignal (i.e., the first signal will be attenuated).

[0526] 5.3.1.2 Structural Description.

[0527] The design and use of a linear amplifier is well known to thoseskilled in the relevant art(s). A linear amplifier may be designed andfabricated from discrete components, or it may be purchased “off theshelf.”

[0528] Exemplary amplifiers are seen in FIG. 48. In the exemplarycircuit diagram of FIG. 48A, six transistors are used in a widebandamplifier. In the more basic exemplary circuit of FIG. 48B, theamplifier is composed of one transistor, four resistors, and acapacitor. Those skilled in the relevant art(s) will recognize thatnumerous alternative designs may be used.

[0529] 5.3.2 Other Implementations.

[0530] The implementations described above are provided for purposes ofillustration. These implementations are not intended to limit theinvention. Alternate implementations, differing slightly orsubstantially from those described herein, will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.Such alternate implementations fall within the scope and spirit of thepresent invention.

[0531] 6. Receiver/Transmitter System.

[0532] The present invention is for a method and system forup-conversion of electromagnetic signals. In one embodiment, theinvention is a source of a stable high frequency reference signal. In asecond embodiment, the invention is a transmitter.

[0533] This section describes a third embodiment. In the thirdembodiment, the transmitter of the present invention to be used in areceiver/transmitter communications system. This third embodiment mayalso be referred to as the communications system embodiment, and thecombined receiver/transmitter circuit is referred to as a “transceiver.”There are several alternative enhancements to the communications systemsembodiment.

[0534] The following sections describe systems and methods related toexemplary embodiments for a receiver/transmitter system. It should beunderstood that the invention is not limited to the particularembodiments described below. Equivalents, extensions, variations,deviations, etc., of the following will be apparent to persons skilledin the relevant art(s) based on the teachings contained herein. Suchequivalents, extensions, variations, deviations, etc., are within thescope and spirit of the present invention.

[0535] 6.1 High Level Description.

[0536] This section provides a high-level description of areceiver/transmitter system according to the present invention. Theimplementations are described herein for illustrative purposes, and arenot limiting. In particular, any number of functional and structuralimplementations may be used, several of which are described in thissection. The details of such functional and structural implementationswill be apparent to persons skilled in the relevant art(s) based on theteachings contained herein.

[0537] According to a first embodiment of the transmitter of the presentinvention is used with a traditional superheterodyne receiver. In thisembodiment, the transmitter and the receiver can operate either in afull-duplex mode or in a half-duplex mode. In a full duplex mode, thetransceiver can transmit and receive simultaneously. In the half-duplexmode, the transceiver can either transmit or receive, but cannot do bothsimultaneously. The full-duplex and the half-duplex modes will bediscussed together for this embodiment.

[0538] A second embodiment of the transceiver is for the transmitter ofthe present invention to be used with a universal frequency downconversion circuit being used as a receiver. In this embodiment thetransceiver is used in a half-duplex mode.

[0539] A third embodiment of the transceiver is for the transmitter ofthe present invention to be used with a universal frequency downconversion circuit, where the transceiver is used in a full-duplex mode.

[0540] These embodiments of the transceiver are described below.

[0541] 6.2 Exemplary Embodiments and Implementation Examples.

[0542] Various embodiments related to the method(s) and structure(s)described above and exemplary operational and/or structuralimplementations related to those embodiments are presented in thissection (and its subsections). These embodiments, components, andmethods are described herein for purposes of illustration, and notlimitation. The invention is not limited to these embodiments or to theparticular examples of components and methods described herein.Alternatives (including equivalents, extensions, variations, deviations,etc., of those described herein) will be apparent to persons skilled inthe relevant art(s) based on the teachings contained herein. Suchalternatives fall within the scope and spirit of the present invention,and the invention is intended and adapted to include such alternatives.

[0543] 6.2.1 First Embodiment: The Transmitter of the Present InventionBeing Used in a Circuit with a Superheterodyne Receiver.

[0544] A typical superheterodyne receiver is shown in FIG. 49. Anantenna 4904 receives a signal 4902. Typically, signal 4902 is a radiofrequency (RF) signal which is routed to a filter 4910 and an amplifier4908. The filter 4910 removes all but a frequency range that includesthe desired frequency, and the amplifier 4908 ensures that the signalstrength will be sufficient for further processing. The output ofamplifier 4908 is a signal 4911.

[0545] A local oscillator 4914 generates an oscillating signal 4916which is combined with signal 4911 by mixer 4912. The output of mixer4912 is a signal 4934 which is amplified by an amplifier 4918 andfiltered by a filter 4920. The purpose of amplifier 4918 is to ensurethat the strength of signal 4934 is sufficient for further processing,and the purpose of filter 4920 is to remove the undesired frequencies.

[0546] A second local oscillator 4924 generates a second oscillatingsignal 4926 which is combined with the amplified/filtered signal 4934 bya mixer 4922. The output of mixer 4922 is signal 4936. Again, anamplifier 4928 and a filter 4930 ensure that the signal 4936 is at thedesired amplitude and frequency. The resulting signal is then routed todecoder 4932 where the intelligence is extracted to obtain basebandsignal 4938.

[0547] Signal 4934 is referred to as the first intermediate frequency(IF) signal, and signal 4936 is referred to as the second IF signal.Thus, the combination of local oscillator 4914 and mixer 4912 can bereferred to as the first IF stage, and the combination of localoscillator 4924 and mixer 4922 can be referred to as the second IFstage.

[0548] Exemplary frequencies for the circuit of FIG. 49 are as follows.Signal 4902 may be 900 MHz. The oscillator signal 4916 may be at 830MHz, which will result in the frequency of the first IF signal, signal4934, being at 70 MHz. If the second oscillating signal 4926 is at 59MHz, the second IF signal, signal 4936, would be at 11 MHz. Thisfrequency is typical of second IF frequencies.

[0549] Other superheterodyne receiver configurations are well known andthese can be used in the transceiver embodiments of the invention. Also,the exemplary frequencies mentioned above are provide for illustrativepurposes only, and are not limiting.

[0550]FIG. 50 shows a transmitter of the present invention in atransceiver circuit with a typical superheterodyne receiver.Accordingly, FIG. 50 illustrates an exemplary transceiver circuit of theinvention. The transceiver includes a receiver module 5001, which isimplemented using any superheterodyne receiver configuration, and whichis described above. The transceiver also includes a transmitter module5003, which is described below.

[0551] In the FM and PM modes, an information signal 5004 modulates anintermediate signal to produce the oscillating signal 5002. Oscillatingsignal 5002 is shaped by signal shaper 5010 to produce a string ofpulses 5008 (see the discussion above regarding the benefits of harmonicenhancement). The string of pulses 5008 drives the switch module 5012.In the FM/PM modes, a bias/reference signal 5006 is also received byswitch module 5012. The output of switch module 5012 is a harmonicallyrich signal 5022. Harmonically rich signal 5022 is comprised of aplurality of sinusoidal components, and is routed to a “high Q” filterthat will remove all but the desired output frequency(ies). The desiredoutput frequency 5024 is amplified by an amplifier 5016 and routed to atransmission module 5018 which outputs a transmission signal 5026 whichis routed to a duplexer 5020. The purpose of duplexer 5020 is to permita single antenna to be used simultaneously for both receiving andtransmitting signals. The combination of received signal 4902 andtransmission signal 5026 is a duplexed signal 5028.

[0552] In the AM mode, the same circuit of FIG. 50 applies, except: (1)an information signal 5030 replaces information signal 5004; (2)bias/reference signal 5006 is a function of the information signal 5030;and (3) oscillating signal 5002 is not modulated.

[0553] This description is for the full-duplex mode of the transceiverwherein the transmitting portion of the communications system is aseparate circuit than the receiver portion. A possible embodiment of ahalf-duplex mode is described below.

[0554] Alternate embodiments of the transceiver are possible. Forexample, FIGS. 51A through 51D illustrate an embodiment of thetransceiver wherein it may be desired, for cost or other considerations,for an oscillator to be shared by both the transmitter portion and thereceiver portion of the circuit. To do this, a trade off must be made inselecting the frequency of the oscillator. In FIG. 51A, a localoscillator 5104 generates an oscillating signal 5106 which is mixed withsignal 4911 to generate a first IF signal 5108. A local oscillator 5110generates a second oscillating signal 5112 which is mixed with the firstIF signal 5108 to generate a second IF signal 5114. For the exampleherein, the frequencies of the oscillating signals 5106 and 5112 will belower than the frequencies of signal 4911 and first IF signal 5108,respectively. (One skilled in the relevant art(s) will recognize that,because the mixers 4912 and 4922 create both the sum and the differenceof the signals they receive, the oscillator frequencies could be higherthan the signal frequencies.)

[0555] As described in the example above, a typical second IF frequencyis 11 MHz. The selection of this IF frequency is less flexible than isthe selection of the first IF frequency, since the second IF frequencyis routed to a decoder where the signal is demodulated and decoded.Typically, demodulators and decoders are designed to receive signals ata predetermined, fixed frequency, e.g., 11 MHz. If this is the case, thecombination of the first IF signal 5108 and the second oscillatingsignal 5112 must generate a second IF signal with a second IF frequencyof 11 MHz. Recall that the received signal 4902 was 900 MHz in theexample above. To achieve the second IF signal frequency of 11 MHz, thefrequencies of the oscillating signals 4916 and 4926 were set at 830 MHzand 59 MHz. Before setting the frequencies of the oscillating signals5106 and 5112, the desired frequency of the transmitted signal must bedetermined. If it, too, is 900 MHz, then the frequency of theoscillating signal that causes the switch in the present invention toopen and close must be a “sub-harmonic” of 900 MHz. That is, it must bethe quotient of 900 MHz divided by an integer. (In other words, 900 MHzmust be a harmonic of the oscillating signal that drives the switch.)The table below is a list of some of the sub-harmonics of 900 MHz:sub-harmonic frequency 1^(st) 900 MHz 2^(nd) 450 3^(rd) 300 4^(th) 2255^(th) 180 10^(th)  90 15^(th)  60

[0556] Recall that the frequency of the second oscillating signal 4926in FIGS. 49 and 50 was 59 MHz. Notice that the frequency of the 15^(th)sub-harmonic is 60 MHz. If the frequency of oscillating signal 5112 ofFIG. 51 were set at 60 MHz, it could also be used as the oscillatingsignal to operate the switches in switch module 5126 of FIG. 51B andswitch module 5136 of FIG. 51C. If this were done, the frequency of thefirst IF signal would be 71 MHz (rather than 70 MHz in the previousexample of a stand-alone receiver), as indicated below: $\begin{matrix}{{{First}\quad {IF}\quad {frequency}} = \quad {{{Second}\quad {IF}\quad {frequency}} +}} \\{\quad {{Second}\quad {oscillating}\quad {frequency}}} \\{= \quad {{11\quad {MHz}} + {60\quad {MHz}}}} \\{= \quad {71\quad {MHz}}}\end{matrix}$

[0557] The frequency of the first oscillating signal 5106 can bedetermined from the values of the first IF frequency and the frequencyof the received signal 4902. In this example, the frequency of thereceived signal is 900 MHz and the frequency of the first IF signal is71 MHz. Therefore, the frequency of the first oscillating signal 5106must be 829 MHz, as indicated below: $\begin{matrix}{{{First}\quad {oscillating}\quad {frequency}} = \quad {{{Freq}\quad {of}\quad {received}\quad {signal}} -}} \\{\quad {{First}\quad {IF}\quad {freq}}} \\{= \quad {{900\quad {MHz}} - {71\quad {MHz}}}} \\{= \quad {829\quad {MHz}}}\end{matrix}$

[0558] Thus the frequencies of the oscillating signals 5106 and 5112 are829 MHz and 60 MHz, respectively.

[0559] In FIG. 51B, the PM embodiment is shown. The second oscillatingsignal 5112 is routed to a phase modulator 5122 where it is modulated bythe information signal 5120 to generate a PM signal 5132. PM signal 5132is routed to a harmonic enhancement module 5124 to create a string ofpulses 5133. The string of pulses 5133 is also a phase modulated signaland is used to cause the switch in switch module 5126 to open and close.Also entering switch module 5126 is a bias signal 5128. The output ofswitch module 5126 is a harmonically rich signal 5134.

[0560] In FIG. 5IC, the AM embodiment is shown. The second oscillatingsignal 5112 directly enters the harmonic enhancement module 5124 tocreate a string of pulses 5138. String of pulses 5138 (not modulated inthis embodiment) then enters a switch module 5136 where it causes aswitch to open and close. Also entering switch module 5136 is areference signal 5140. Reference signal is created by summing module5130 by combining information signal 5120 with bias signal 5128. It iswell known to those skilled in the relevant art(s) that the informationsignal 5120 may be used as the reference signal without being combinedwith the bias signal 5128. The output of switch module 5136 is aharmonically rich signal 5134.

[0561] The scope of the invention includes an FM embodiment wherein theoscillator 5110 of the receiver circuit is used as a source for anoscillating signal for the transmitter circuit. In the embodimentsdiscussed above, the FM embodiment requires a voltage controlledoscillator (VCO) rather than a simple local oscillator. There arecircuit designs that would be apparent to those skilled in the relevantart(s) based on the discussion contained herein, wherein a VCO is usedin place of a local oscillator in the receiver circuit.

[0562] In FIG. 51D, the harmonically rich signal 5134 is filtered by afilter 5142, which removes all but the desired output frequency 5148.The desired output frequency 5148 is amplified by amplifier module 5146and routed to transmission module 5150. The output of transmissionmodule 5150 is a transmission signal 5144. Transmission signal 5144 isthen routed to the antenna 4904 for transmission.

[0563] Those skilled in the relevant art(s) will understand that thereare numerous combinations of oscillator frequencies, stages, andcircuits that will meet the scope and intent of this invention. Thus,the description included herein is for illustrative purposes only andnot meant to be limiting.

[0564] 6.2.2 Second Embodiment: The Transmitter of the Present InventionBeing Used with a Universal Frequency Down-Converter in a Half-DuplexMode.

[0565] An exemplary receiver using universal frequency down conversiontechniques is shown in FIG. 52 and described in section 6.3, below. Anantenna 5202 receives an electromagnetic (EM) signal 5220. EM signal5220 is routed through a capacitor 5204 to a first terminal of a switch5210. The other terminal of switch 5210 is connected to ground 5212 inthis exemplary embodiment. A local oscillator 5206 generates anoscillating signal 5228 which is routed through a pulse shaper 5208. Theresult is a string of pulses 5230. The selection of the oscillator 5206and the design of the pulse shaper 5208 control the frequency and pulsewidth of the string of pulses 5230. The string of pulses 5230 controlthe opening and closing of switch 5210. As a result of the opening andclosing of switch 5210, a down converted signal 5222 results. Downconverted signal 5222 is routed through an amplifier 5214 and a filter5216, and a filtered signal 5224 results. In a preferred embodiment,filtered signal 5224 is at baseband, and a decoder 5218 may only beneeded to convert digital to analog or to remove encryption beforeoutputting the baseband information signal. This then is a universalfrequency down conversion receiver operating in a direct down conversionmode, in that it receives the EM signal 5220 and down converts it tobaseband signal 5226 without requiring an IF or a demodulator. In analternate embodiment, the filtered signal 5224 may be at an “offset”frequency. That is, it is at an intermediate frequency, similar to thatdescribed above for the second IF signal in a typical superheterodynereceiver. In this case, the decoder 5218 would be used to demodulate thefiltered signal so that it could output a baseband signal 5226.

[0566] An exemplary transmitter using the present invention is shown inFIG. 53. In the FM and PM embodiments, an information signal 5302modulates an oscillating signal 5306 which is routed to a pulse shapingcircuit 5310 which outputs a string of pulses 5311. The string of pulses5311 controls the opening and closing of the switch 5312. One terminalof switch 5312 is connected to ground 5314, and the second terminal ofswitch 5312 is connected through a resistor 5330 to a bias/referencesignal 5308. In the FM and PM modes, bias/reference signal 5308 ispreferably a non-varying signal, often referred to simply as the biassignal. In the AM mode, the oscillating signal 5306 is not modulated,and the bias/reference signal is a function of the information signal5304. In one embodiment, information signal 5304 is combined with a biasvoltage to generate the reference signal 5308. In an alternateembodiment, the information signal 5304 is used without being combinedwith a bias voltage. Typically, in the AM mode, this bias/referencesignal is referred to as the reference signal to distinguish it from thebias signal used in the FM and PM modes. The output of switch 5312 is aharmonically rich signal 5316 which is routed to a “high Q” filter whichremoves the unwanted frequencies that exist as harmonic components ofharmonically rich signal 5316. Desired frequency 5320 is amplified byamplifier module 5322 and routed to transmission module 5324 whichoutputs a transmission signal 5326. Transmission signal is output byantenna 5328 in this embodiment.

[0567] For the FM and PM modulation modes, FIGS. 54A, 54B, and 54C showthe combination of the present invention of the transmitter and theuniversal frequency down-conversion receiver in the half-duplex modeaccording to an embodiment of the invention. That is, the transceivercan transmit and receive, but it cannot do both simultaneously. It usesa single antenna 5402, a single oscillator 5444/5454 (depending onwhether the transmitter is in the FM or PM modulation mode), a singlepulse shaper 5438, and a single switch 5420 to transmit and to receive.In the receive function, “Receiver/transmitter” (R/T) switches 5406,5408, and 5446/5452 (FM or PM) would all be in the receive position,designated by (R). The antenna 5402 receives an EM signal 5404 androutes it through a capacitor 5407. In the FM modulation mode,oscillating signal 5436 is generated by a voltage controlled oscillator(VCO) 5444. Because the transceiver is performing the receive function,switch 5446 connects the input to the VCO 5444 to ground 5448. Thus, VCO5444 will operate as if it were a simple oscillator. In the PMmodulation mode, oscillating signal 5436 is generated by localoscillator 5454 which is routed through phase modulator 5456. Since thetransceiver is performing the receive function, switch 5452 is connectedto ground 5448, and there is no modulating input to phase modulator.Thus, local oscillator 5454 and phase modulator 5456 operate as if theywere a simple oscillator. One skilled in the relevant art(s) willrecognize based on the discussion contained herein that there arenumerous embodiments wherein an oscillating signal 5436 can be generatedto control the switch 5420.

[0568] Oscillating signal 5436 is shaped by pulse shaper 5438 to producea string of pulses 5440. The string of pulses 5440 cause the switch 5420to open and close. As a result of the switch opening and closing, a downconverted signal 5409 is generated. The down converted signal 5409 isamplified and filtered to create a filtered signal 5413. In anembodiment, filtered signal 5413 is at baseband and, as a result of thedown conversion, is demodulated. Thus, a decoder 5414 may not berequired except to convert digital to analog or to decrypt the filteredsignal 5413. In an alternate embodiment, the filtered signal 5413 is atan “offset” frequency, so that the decoder 5414 is needed to demodulatethe filtered signal and create a demodulated baseband signal.

[0569] When the transceiver is performing the transmit function, the R/Tswitches 5406, 5408, and 5446/5452 (FM or PM) are in the (T) position.In the FM modulation mode, an information signal 5450 is connected byswitch 5446 to VCO 5444 to create a frequency modulated oscillatingsignal 5436. In the PM modulation mode switch 5452 connects informationsignal 5450 to the phase modulator 5456 to create a phase modulatedoscillating signal 5436. Oscillation signal 5436 is routed through pulseshaper 5438 to create a string of pulses 5440 which in turn cause switch5420 to open and close. One terminal of switch 5420 is connected toground 5442 and the other is connected through switch R/T 5408 andresistor 5423 to a bias signal 5422. The result is a harmonically richsignal 5424 which is routed to a “high Q” filter 5426 which removes theunwanted frequencies that exist as harmonic components of harmonicallyrich signal 5424. Desired frequency 5428 is amplified by amplifiermodule 5430 and routed to transmission module 5432 which outputs atransmission signal 5434. Again, because the transceiver is performingthe transmit function, R/T switch 5406 connects the transmission signalto the antenna 5402.

[0570] In the AM modulation mode, the transceiver operates in the halfduplex mode as shown in FIG. 55. The only distinction between thismodulation mode and the FM and PM modulation modes described above, isthat the oscillating signal 5436 is generated by a local oscillator5502, and the switch 5420 is connected through the R/T switch 5408 andresistor 5423 to a reference signal 5506. Reference signal 5506 isgenerated when information signal 5450 and bias signal 5422 are combinedby a summing module 5504. It is well known to those skilled in therelevant art(s) that the information signal 5450 may be used as thereference signal 5506 without being combined with the bias signal 5422,and may be connected directly (through resistor 5423 and R/T switch5408) to the switch 5420.

[0571] 6.2.3 Third Embodiment: The Transmitter of the Present InventionBeing Used with a Universal Frequency Down Converter in a Full-DuplexMode.

[0572] The full-duplex mode differs from the half-duplex mode in thatthe transceiver can transmit and receive simultaneously. Referring toFIG. 56, to achieve this, the transceiver preferably uses a separatecircuit for each function. A duplexer 5604 is used in the transceiver topermit the sharing of an antenna 5602 for both the transmit and receivefunctions.

[0573] The receiver function performs as follows. The antenna 5602receives an EM signal 5606 and routes it through a capacitor 5607 to oneterminal of a switch 5626. The other terminal of switch 5626 isconnected to ground 5628, and the switch is driven as a result of astring of pulses 5624 created by local oscillator 5620 and pulse shaper5622. The opening and closing of switch 5626 generates a down convertedsignal 5614. Down converted signal 5614 is routed through a amplifier5608 and a filter 5610 to generate filtered signal 5616. Filtered signal5616 may be at baseband and be demodulated or it may be at an “offset”frequency. If filtered signal 5616 is at an offset frequency, decoder5612 will demodulate it to create the demodulated baseband signal 5618.In a preferred embodiment, however, the filtered signal 5616 will be ademodulated baseband signal, and decoder 5612 may not be required exceptto convert digital to analog or to decrypt filtered signal 5616. Thisreceiver portion of the transceiver can operate independently from thetransmitter portion of the transceiver.

[0574] The transmitter function is performed as follows. In the FM andPM modulation modes, an information signal 5648 modulates an oscillatingsignal 5630. In the AM modulation mode, the oscillating signal 5630 isnot modulated. The oscillating signal is shaped by pulse shaper 5632 anda string of pulses 5634 is created. This string of pulses 5634 causes aswitch 5636 to open and close. One terminal of switch 5636 is connectedto ground 5638, and the other terminal is connected through a resistor5647 to a bias/reference signal 5646. In the FM and PM modulation modes,bias/reference signal 5646 is referred to as a bias signal 5646, and itis substantially non-varying. In the AM modulation mode, an informationsignal 5650 may be combined with the bias signal to create what isreferred to as the reference signal 5646. The reference signal 5646 is afunction of the information signal 5650. It is well known to thoseskilled in the relevant art(s) that the information signal 5650 may beused as the bias/reference signal 5646 directly without being summedwith a bias signal. A harmonically rich signal 5652 is generated and isfiltered by a “high Q” filter 5640, thereby producing a desired signal5654. The desired signal 5654 is amplified by amplifier 5642 and routedto transmission module 5644. The output of transmission module 5644 istransmission signal 5656. Transmission signal 5656 is routed to duplexer5604 and then transmitted by antenna 5602. This transmitter portion ofthe transceiver can operate independently from the receiver portion ofthe transceiver.

[0575] Thus, as described above, the transceiver embodiment the presentinvention as shown in FIG. 56 can perform full-duplex communications inall modulation modes.

[0576] 6.2.4 Other Embodiments and Implementations.

[0577] Other embodiments and implementations of the receiver/transmitterof the present invention would be apparent to one skilled in therelevant art(s) based on the discussion herein.

[0578] The embodiments and implementations described above are providedfor purposes of illustration. These embodiments and implementations arenot intended to limit the invention. Alternatives, differing slightly orsubstantially from those described herein, will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.Such alternate embodiments and implementations fall within the scope andspirit of the present invention.

[0579] 6.3 Summary Description of Down-conversion Using a UniversalFrequency Translation Module.

[0580] The following discussion describes down-converting using aUniversal Frequency Translation Module. The down-conversion of an EMsignal by aliasing the EM signal at an aliasing rate is fully describedin co-pending U.S. patent application entitled “Method and System forDown-converting an Electromagnetic Signal,” application Ser. No. ______,Attorney Docket Number 1744.0010000, the full disclosure of which isincorporated herein by reference. A relevant portion of the abovementioned patent application is summarized below to describedown-converting an input signal to produce a down-converted signal thatexists at a lower frequency or a baseband signal.

[0581]FIG. 64A illustrates an aliasing module 6400 for down-conversionusing a universal frequency translation (UFT) module 6402 whichdown-converts an EM input signal 6404. In particular embodiments,aliasing module 6400 includes a switch 6408 and a capacitor 6410. Theelectronic alignment of the circuit components is flexible. That is, inone implementation, the switch 6408 is in series with input signal 6404and capacitor 6410 is shunted to ground (although it may be other thanground in configurations such as differential mode). In a secondimplementation (see FIGS. 64A-1), the capacitor 6410 is in series withthe input signal 6404 and the switch 6408 is shunted to ground (althoughit may be other than ground in configurations such as differentialmode). Aliasing module 6400 with UFT module 6402 can be easily tailoredto down-convert a wide variety of electromagnetic signals using aliasingfrequencies that are well below the frequencies of the EM input signal6404.

[0582] In one implementation, aliasing module 6400 down-converts theinput signal 6404 to an intermediate frequency (IF) signal. In anotherimplementation, the aliasing module 6400 down-converts the input signal6404 to a demodulated baseband signal. In yet another implementation,the input signal 6404 is a frequency modulated (FM) signal, and thealiasing module 6400 down-converts it to a non-FM signal, such as aphase modulated (PM) signal or an amplitude modulated (AM) signal. Eachof the above implementations is described below.

[0583] In an embodiment, the control signal 6406 includes a train ofpulses that repeat at an aliasing rate that is equal to, or less than,twice the frequency of the input signal 6404 In this embodiment, thecontrol signal 6406 is referred to herein as an aliasing signal becauseit is below the Nyquist rate for the frequency of the input signal 6404.Preferably, the frequency of control signal 6406 is much less than theinput signal 6404.

[0584] The train of pulses 6418 as shown in FIG. 64D controls the switch6408 to alias the input signal 6404 with the control signal 6406 togenerate a down-converted output signal 6412. More specifically, in anembodiment, switch 6408 closes on a first edge of each pulse 6420 ofFIG. 64D and opens on a second edge of each pulse. When the switch 6408is closed, the input signal 6404 is coupled to the capacitor 6410, andcharge is transferred from the input signal to the capacitor 6410. Thecharge stored during successive pulses forms down-converted outputsignal 6412.

[0585] Exemplary waveforms are shown in FIGS. 64B-64F.

[0586]FIG. 64B illustrates an analog amplitude modulated (AM) carriersignal 6414 that is an example of input signal 6404. For illustrativepurposes, in FIG. 64C, an analog AM carrier signal portion 6416illustrates a portion of the analog AM carrier signal 6414 on anexpanded time scale. The analog AM carrier signal portion 6416illustrates the analog AM carrier signal 6414 from time t₀ to time t₁.

[0587]FIG. 64D illustrates an exemplary aliasing signal 6418 that is anexample of control signal 6406. Aliasing signal 6418 is on approximatelythe same time scale as the analog AM carrier signal portion 6416. In theexample shown in FIG. 64D, the aliasing signal 6418 includes a train ofpulses 6420 having negligible apertures that tend towards zero (theinvention is not limited to this embodiment, as discussed below). Thepulse aperture may also be referred to as the pulse width as will beunderstood by those skilled in the art(s). The pulses 6420 repeat at analiasing rate, or pulse repetition rate of aliasing signal 6418. Thealiasing rate is determined as described below, and further described inco-pending U.S. patent application entitled “Method and System forDown-converting an Electromagnetic Signal,” application Ser. No. ______, Attorney Docket Number 1744.0010000.

[0588] As noted above, the train of pulses 6420 (i.e., control signal6406) control the switch 6408 to alias the analog AM carrier signal 6416(i.e., input signal 6404) at the aliasing rate of the aliasing signal6418. Specifically, in this embodiment, the switch 6408 closes on afirst edge of each pulse and opens on a second edge of each pulse. Whenthe switch 6408 is closed, input signal 6404 is coupled to the capacitor6410, and charge is transferred from the input signal 6404 to thecapacitor 6410. The charge transferred during a pulse is referred toherein as an under-sample. Exemplary under-samples 6422 formdown-converted signal portion 6424 (FIG. 64E) that corresponds to theanalog AM carrier signal portion 6416 (FIG. 64C) and the train of pulses6420 (FIG. 64D). The charge stored during successive under-samples of AMcarrier signal 6414 form the down-converted signal 6424 (FIG. 64E) thatis an example of down-converted output signal 6412 (FIG. 64A). In FIG.64F a demodulated baseband signal 6426 represents the demodulatedbaseband signal 6424 after filtering on a compressed time scale. Asillustrated, down-converted signal 6426 has substantially the same“amplitude envelope” as AM carrier signal 6414. Therefore, FIGS. 64B-64Fillustrate down-conversion of AM carrier signal 6414.

[0589] The waveforms shown in FIGS. 64B-64F are discussed herein forillustrative purposes only, and are not limiting. Additional exemplarytime domain and frequency domain drawings, and exemplary methods andsystems of the invention relating thereto, are disclosed in co-pendingU.S. patent application entitled “Method and System for Down-convertingan Electromagnetic Signal,” application Ser. No. ______ . AttorneyDocket Number 1744.0010000.

[0590] The aliasing rate of control signal 6406 determines whether theinput signal 6404 is down-converted to an IF signal, down-converted to ademodulated baseband signal, or down-converted from an FM signal to a PMor an AM signal. Generally, relationships between the input signal 6404,the aliasing rate of the control signal 6406, and the down-convertedoutput signal 6412 are illustrated below:

(Freq. of input signal 6404)=n·(Freq. of control signal 6406)±(Freq. ofdown-converted output signal 6412)

[0591] For the examples contained herein, only the “+” condition will bediscussed. The value of n represents a harmonic or sub-harmonic of inputsignal 6404 (e.g., n=0.5, 1, 2, 3, . . . ).

[0592] When the aliasing rate of control signal 6406 is off-set from thefrequency of input signal 6404, or off-set from a harmonic orsub-harmonic thereof, input signal 6404 is down-converted to an IFsignal. This is because the under-sampling pulses occur at differentphases of subsequent cycles of input signal 6404. As a result, theunder-samples form a lower frequency oscillating pattern. If the inputsignal 6404 includes lower frequency changes, such as amplitude,frequency, phase, etc., or any combination thereof, the charge storedduring associated under-samples reflects the lower frequency changes,resulting in similar changes on the down-converted IF signal. Forexample, to down-convert a 901 MHz input signal to a 1 MHz IF signal,the frequency of the control signal 6406 would be calculated as follows:

(Freq _(input) −Freq _(IF))/n=Freq _(control)

(901 MHz−1 MHz)/n=900/n

[0593] For n=0.5, 1, 2, 3, 4, etc., the frequency of the control signal6406 would be substantially equal to 1.8 GHz, 900 MHz, 450 MHz, 300 MHz,225 MHz, etc.

[0594] Exemplary time domain and frequency domain drawings, illustratingdown-conversion of analog and digital AM, PM and FM signals to IFsignal, and exemplary methods and systems thereof, are disclosed inco-pending U.S. patent application entitled “Method and System forDown-converting an Electromagnetic Signal,” application Ser. No. ______,Attorney Docket Number 1744.0010000.

[0595] Alternatively, when the aliasing rate of the control signal 6406is substantially equal to the frequency of the input signal 6404, orsubstantially equal to a harmonic or sub-harmonic thereof, input signal6404 is directly down-converted to a demodulated baseband signal. Thisis because, without modulation, the under-sampling pulses occur at thesame point of subsequent cycles of the input signal 6404. As a result,the under-samples form a constant output baseband signal. If the inputsignal 6404 includes lower frequency changes, such as amplitude,frequency, phase, etc., or any combination thereof, the charge storedduring associated under-samples reflects the lower frequency changes,resulting in similar changes on the demodulated baseband signal. Forexample, to directly down-convert a 900 MHz input signal to ademodulated baseband signal (i.e., zero IF), the frequency of thecontrol signal 6406 would be calculated as follows:

(Freq _(input) −Freq _(IF))/n=Freq _(control)

(900 MHz−0 MHz)/n=900 MHz/n

[0596] For n=0.5, 1, 2, 3, 4, etc., the frequency of the control signal6406 should be substantially equal to 1.8 GHz, 900 MHz, 450 MHz, 300MHz, 225 MHz, etc.

[0597] Exemplary time domain and frequency domain drawings, illustratingdirect down-conversion of analog and digital AM and PM signals todemodulated baseband signals, and exemplary methods and systems thereof,are disclosed in the co-pending U.S. patent application entitled “Methodand System for Down-converting an Electromagnetic Signal,” applicationSer. No. ______, Attorney Docket Number 1744.0010000.

[0598] Alternatively, to down-convert an input FM signal to a non-FMsignal, a frequency within the FM bandwidth must be down-converted tobaseband (i.e., zero IF). As an example, to down-convert a frequencyshift keying (FSK) signal (a sub-set of FM) to a phase shift keying(PSK) signal (a subset of PM), the mid-point between a lower frequencyF₁ and an upper frequency F₂ (that is, [(F₁+F₂)÷2]) of the FSK signal isdown-converted to zero IF. For example, to down-convert an FSK signalhaving F₁ equal to 899 MHz and F₂ equal to 901 MHz, to a PSK signal, thealiasing rate of the control signal 6406 would be calculated as follows:$\begin{matrix}{{{Frequency}\quad {of}\quad {the}\quad {input}} = \quad {\left( {F_{1} + F_{2}} \right) \div 2}} \\{= \quad {\left( {{899\quad {MHz}} + {901\quad {MHz}}} \right) \div 2}} \\{= \quad {900\quad {MHz}}}\end{matrix}$

[0599] Frequency of the down-converted signal=0 (i.e., baseband)

(Freq _(input) −Freq _(IF))/n=Freq _(control)

(900 MHz−0 MHz)/n=900 MHz/n

[0600] For n=0.5, 1, 2, 3, etc., the frequency of the control signal6406 should be substantially equal to 1.8 GHz, 900 MHz, 450 MHz, 300MHz, 225 MHz, etc. The frequency of the down-converted PSK signal issubstantially equal to one half the difference between the lowerfrequency F₁ and the upper frequency F₂.

[0601] As another example, to down-convert a FSK signal to an amplitudeshift keying (ASK) signal (a subset of AM), either the lower frequencyF₁ or the upper frequency F₂ of the FSK signal is down-converted to zeroIF. For example, to down-convert an FSK signal having F₁ equal to 900MHz and F₂ equal to 901 MHz, to an ASK signal, the aliasing rate of thecontrol signal 6406 should be substantially equal to:

(900 MHz−0 MHz)/n=900 MHz/n, or

(901 MHz−0 MHz)/n=901 MHz/n.

[0602] For the former case of 900 MHz/n, and for n=0.5, 1, 2, 3, 4,etc., the frequency of the control signal 6406 should be substantiallyequal to 1.8 GHz, 900 MHz, 450 MHz, 300 MHz, 225 MHz, etc. For thelatter case of 901 MHz/n, and for n=0.5, 1, 2, 3, 4, etc., the frequencyof the control signal 6406 should be substantially equal to 1.802 GHz,901 MHz, 450.5 MHz, 300.333 MHz, 225.25 MHz, etc. The frequency of thedown-converted AM signal is substantially equal to the differencebetween the lower frequency F₁ and the upper frequency F₂ (i.e., 1 MHz).

[0603] Exemplary time domain and frequency domain drawings, illustratingdown-conversion of FM signals to non-FM signals, and exemplary methodsand systems thereof, are disclosed in the co-pending U.S. patentapplication entitled “Method and System for Down-converting anElectromagnetic Signal,” application Ser. No. ______, Attorney DocketNumber 1744.0010000.

[0604] In an embodiment, the pulses of the control signal 6406 havenegligible apertures that tend towards zero. This makes the UFT module6402 a high input impedance device. This configuration is useful forsituations where minimal disturbance of the input signal may be desired.

[0605] In another embodiment, the pulses of the control signal 6406 havenon-negligible apertures that tend away from zero. This makes the UFTmodule 6402 a lower input impedance device. This allows the lower inputimpedance of the UFT module 6402 to be substantially matched with asource impedance of the input signal 6404. This also improves the energytransfer from the input signal 6404 to the down-converted output signal6412, and hence the efficiency and signal to noise (s/n) ratio of UFTmodule 6402.

[0606] Exemplary systems and methods for generating and optimizing thecontrol signal 6406 and for otherwise improving energy transfer and s/nratio, are disclosed in the co-pending U.S. patent application entitled“Method and System for Down-converting an Electromagnetic Signal,”application Ser. No. ______, Attorney Docket Number 1744.0010000.

[0607] 7. Designing a Transmitter According to an Embodiment of thePresent Invention.

[0608] This section (including its subsections) provides a high-leveldescription of an exemplary process to be used to design a transmitteraccording to an embodiment of the present invention. The techniquesdescribed herein are also applicable to designing a frequencyup-converter for any application, and for designing the applicationsthemselves. The descriptions are contained herein for illustrativepurposes and are not limiting. Alternatives (including equivalents,extensions, variations, deviations, etc., of those described herein)will be apparent to persons skilled in the relevant art(s) based on theteachings contained herein. Such alternatives fall within the scope andspirit of the present invention, and the invention is intended andadapted to include such alternative.

[0609] The discussion herein describes an exemplary process to be usedto design a transmitter according to an embodiment of the presentinvention. An exemplary circuit for a transmitter of the presentinvention operating in the FM embodiment is shown in FIG. 57A. Likewise,FIG. 57B illustrates the transmitter of the present invention operatingin the PM embodiment, and FIG. 57C shows the transmitter of the presentinvention operating in the AM embodiment. These circuits have been shownin previous figures, but are presented here to facilitate the discussionof the design. As the “I/Q” embodiment of the present invention is asubset of the PM embodiment, it will not be shown in a separate figurehere, since the design approach will be very similar to that for the PMembodiment.

[0610] Depending on the application and on the implementation, some ofthe design considerations may not apply. For example, and withoutlimitation, in some cases it may not be necessary to optimize the pulsewidth or to include an amplifier.

[0611] 7.1 Frequency of the Transmission Signal

[0612] The first step in the design process is to determine thefrequency of the desired transmission signal 5714. This is typicallydetermined by the application for which the transmitter is to be used.The present invention is for a transmitter that can be used for allfrequencies within the electromagnetic (EM) spectrum. For the examplesherein, the explanation will focus on the use of the transmitter in the900 MHz to 950 MHz range. Those skilled in the relevant art(s) willrecognize that the analysis contained herein may be used for anyfrequency or frequency range.

[0613] 7.2 Characteristics of the Transmission Signal

[0614] Once the frequency of the desired transmission signal 5714 isknown, the characteristics of the signal must be determined. Thesecharacteristics include, but are not limited to, whether the transmitterwill operate at a fixed frequency or over a range of frequencies, and ifit is to operate over a range of frequencies, whether those frequenciesare continuous or are divided into discrete “channels.”If the frequencyrange is divided into discrete channels, the spacing between thechannels must be ascertained. As an example, cordless phones operatingin this frequency range may operate on discrete channels that are 50 KHzapart. That is, if the cordless phones operate in the 905 MHz to 915 MHzrange (inclusive), the channels could be found at 905.000, 905.050,905.100, . . . , 914.900, 914.950, and 915.000.

[0615] 7.3 Modulation Scheme.

[0616] Another characteristic that must be ascertained is the desiredmodulation scheme that is to be used. As described above in sections2.1-2.2.4, above, these modulation schemes include FM, PM, AM, etc., andany combination or subset thereof, specifically including the widelyused “I/Q” subset of PM. Just as the frequency of the desiredtransmission signal 5714 is typically determined by the intendedapplication, so too is the modulation scheme.

[0617] 7.4 Characteristics of the Information Signal.

[0618] The characteristics of an information signal 5702 are alsofactors in the design of the transmitter circuit. Specifically, thebandwidth of the information signal 5702 defines the minimum frequencyfor an oscillating signal 5704, 5738, 5744 (for the FM, PM, and AMmodes, respectively).

[0619] 7.5 Characteristics of the Oscillating Signal.

[0620] The desired frequency of the oscillating signal 5704, 5738, 5744is also a function of the frequency and characteristics of the desiredtransmission signal 5714. Also, the frequency and characteristics of thedesired transmission signal 5714 are factors in determining the pulsewidth of the pulses in a string of pulses 5706. Note that the frequencyof the oscillating signal 5704, 5738, 5744 is substantially the same asthe frequency of the string of pulses 5706. (An exception, which isdiscussed below, is when a pulse shaping circuit 5722 increases thefrequency of the oscillating signal 5704, 5738, 5744 in a manner similarto that described above in section 4.3.2.) Note also that the frequencyand pulse width of the string of pulses 5706 is substantially the sameas the frequency and pulse width of a harmonically rich signal 5708.

[0621] 7.5.1 Frequency of the Oscillating Signal.

[0622] The frequency of the oscillating signal 5704, 5738, 5744 must bea subharmonic of the frequency of the desired transmission signal 5714.A subharmonic is the quotient obtained by dividing the fundamentalfrequency, in this case the frequency of the desired transmission signal5714, by an integer. When describing the frequency of certain signals,reference is often made herein to a specific value. It is understood bythose skilled in the relevant art(s) that this reference is to thenominal center frequency of the signal, and that the actual signal mayvary in frequency above and below this nominal center frequency based onthe desired modulation technique being used in the circuit. As anexample to be used herein, if the frequency of the desired transmissionsignal is 910 MHz, and it is to be used in an FM mode where, forexample, the frequency range of the modulation is 40 KHz, the actualfrequency of the signal will vary ±20 KHz around the nominal centerfrequency as a function of the information being transmitted. That is,the frequency of the desired transmission signal will actually rangebetween 909.980 MHz and 910.020 MHz.

[0623] The first ten subharmonics of a 910.000 MHz signal are givenbelow. harmonic frequency 1^(st) 910.000 MHz 2^(nd) 455.000 3^(rd)303.333 . . . 4^(th) 227.500 5^(th) 182.000 6^(th) 151.666 . . . 7^(th)130.000 8^(th) 113.750 9^(th) 101.111 . . . 10^(th)  91.000

[0624] The oscillating signal 5704, 5738, 5744 can be at any one ofthese frequencies or, if desired, at a lower subharmonic. For discussionherein, the 9^(th) subharmonic will be chosen. Those skilled in therelevant art(s) will understand that the analysis herein appliesregardless of which harmonic is chosen. Thus the nominal centerfrequency of the oscillating signal 5704, 5738, 5744 will be 101.1111MHz. Recalling that in the FM mode, the frequency of the desiredtransmission signal 5714 is actually 910.000 MHz ±0.020 MHz, it can beshown that the frequency of the oscillating signal 5704 will vary±0.00222 MHz (i.e., from 101.10889 MHz to 101.11333 MHz). The frequencyand frequency sensitivity of the oscillating signal 5704 will drive theselection or design of the voltage controlled oscillator (VCO) 5720.

[0625] Another frequency consideration is the overall frequency range ofthe desired transmission signal. That is, if the transmitter is to beused in the cordless phone of the above example and will transmit on allchannels between 905 MHz and 915 MHz, the VCO 5720 (for the FM mode) orthe local oscillator (LO) 5734 (for the PM and AM modes) will berequired to generate oscillating frequencies 5704, 5738, 5744 that rangefrom 100.5556 MHz to 101.6667 MHz. (That is, the 9^(th) subharmonic of910 MHz ±5 MHz). In some applications, such as the cellular phone, thefrequencies will change automatically, based on the protocols of theoverall cellular system (e.g., moving from one cell to an adjacentcell). In other applications, such as a police radio, the frequencieswill change based on the user changing channels.

[0626] In some applications, different models of the same transmitterwill transmit signals at different frequencies, but each model will,itself, only transmit a single frequency. A possible example of thismight be remote controlled toy cars, where each toy car operates on itsown frequency, but, in order for several toy cars to operate in the samearea, there are several frequencies at which they could operate. Thus,the design of the VCO 5720 or LO 5734 will be such that it is able to betuned to a set frequency when the circuit is fabricated, but the userwill typically not be able to adjust the frequency.

[0627] It is well known to those skilled in the relevant art(s) thatseveral of the criteria to be considered in the selection or design ofan oscillator (VCO 5720 or LO 5734) include, but are not limited to, thenominal center frequency of the desired transmission signal 5714, thefrequency sensitivity caused by the desired modulation scheme, the rangeof all possible frequencies for the desired transmission signal 5714,and the tuning requirements for each specific application. Anotherimportant criterion is the determination of the subharmonic to be used,but unlike the criteria listed above which are dependent on the desiredapplication, there is some flexibility in the selection of thesubharmonic.

[0628] 7.5.2 Pulse Width of the String of Pulses.

[0629] Once the frequency of the oscillating signal 5704, 5738, 5744 hasbeen selected, the pulse width of the pulses in the stream of pulses5706 must be determined. (See sections 4-4.3.4, above, for a discussionof harmonic enhancement and the impact the pulse-width-to-period ratiohas on the relative amplitudes of the harmonics in a harmonically richsignal 5708.) In the example used above, the 9^(th) subharmonic wasselected as the frequency of the oscillating signal 5704, 5738, 5744. Inother words, the frequency of the desired transmission signal will bethe 9^(th) harmonic of the oscillating signal 5704, 5738, 5744. Oneapproach in selecting the pulse width might be to focus entirely on thefrequency of the oscillating signal 5704, 5738, 5744 and select a pulsewidth and observe its operation in the circuit. For the case where theharmonically rich signal 5708 has a unity amplitude, and thepulse-width-to-period ratio is 0.1, the amplitude of the 9^(th) harmonicwill be 0.0219. Looking again at Table 6000 and FIG. 58 it can be seenthat the amplitude of the 9^(th) harmonic is higher than that of the10^(th) harmonic (which is zero) but is less than half the amplitude ofthe 8^(th) harmonic. Because the 9^(th) harmonic does have an amplitude,this pulse-width-to-period ratio could be used with proper filtering.Typically, a different ratio might be selected to try and find a ratiothat would provide a higher amplitude.

[0630] Looking at Eq. 1 in section 4.1.1, it is seen that the relativeamplitude of any harmonic is a function of the number of the harmonicand the pulse-width-to-period ratio of the underlying waveform. Applyingcalculus of variations to the equation, the pulse-width-to-period ratiothat yields the highest amplitude harmonic for any given harmonic can bedetermined.

[0631] From Eq. 1, where A_(n) is the amplitude of the n^(th) harmonic,

A _(n) =[A _(pulse)][(2/π)/n] sin {n·π·(τ/T)]  Eq. 2

[0632] If the amplitude of the pulse, A_(pulse), is set to unity (i.e.,equal to 1), the equation become

A _(n)=[2(n·π)] sin [n·π·(τ/T)]  Eq. 3

[0633] From this equation, it can be seen that for any value of n (theharmonic) the amplitude of that harmonic, A_(n), is a function of thepulse-width-to-period ratio, τ/T. To determine the highest value ofA_(n) for a given value of n, the first derivative of A_(n) with respectto τ/T is taken. This gives the following equations. $\begin{matrix}{{{\delta \left( A_{n} \right)}/{\delta \left( {\tau/T} \right)}} = {\delta {\left\{ {\left\lbrack {2/\left( {n \cdot \pi} \right)} \right\rbrack {\sin \left\lbrack {n \cdot \pi \cdot \left( {\tau/T} \right)} \right\rbrack}} \right\}/{\delta \left( {\tau/T} \right)}}}} & {{Eq}.\quad 4} \\{\text{~~~~~~~~~~~~~~} = {\left\lbrack {2/\left( {n \cdot \pi} \right)} \right\rbrack {\delta\left\lbrack {{\sin \left\lbrack {n \cdot \pi \cdot \left( {\tau/T} \right)} \right\rbrack}{\delta \left( {\tau/T} \right)}} \right.}}} & {{Eq}.\quad 5} \\{\text{~~~~~~~~~~~~~~} = {\left\lbrack {2/\left( {n \cdot \pi} \right)} \right\rbrack {\cos \left\lbrack {n \cdot \pi \cdot \left( {\tau/T} \right)} \right\rbrack}}} & {{Eq}.\quad 6}\end{matrix}$

[0634] From calculus of variations, it is known that when the firstderivative is set equal to zero, the value of the variable that willyield a relative maximum (or minimum) can be determined.

δ(A _(n))/δ(τ/T)=0  Eq. 7

[2/(n·π)] cos [n·π·(τ/T)]=0  Eq. 8

cos [n·π·(τ/T)]=0  Eq. 9

[0635] From trigonometry, it is known that for Eq. 9 to be true,

n·π·(τ/T)=π/2 (or 3π/2, 5π/2, etc.)  Eq. 10

τ/T=(π/2)/(n·π)  Eq. 11

τ/T=1/(2·n) (or 3/(2·n), 5/(2·n), etc.)  Eq. 12

[0636] The above derivation is well known to those skilled in therelevant art(s). From Eq. 12, it can be seen that if thepulse-width-to-period ratio is equal to 1/(2·n), the amplitude of theharmonic should be substantially optimum. For the case of the 9^(th)harmonic, Eq. 12 will yield a pulse-width-to-period ratio of 1/(2·9) or0.0556. For the amplitude of this 9^(th) harmonic, Table 6100 of FIG. 61shows that it is 0.0796. This is an improvement over the previousamplitude for a pulse-width-to-period ratio of 0.1. Table 6100 alsoshows that the 9^(th) harmonic for this pulse-width-to-period ratio hasthe highest amplitude of any 9^(th) harmonic, which bears out thederivation above. The frequency spectrum for a pulse-width-to-periodratio of 0.0556 is shown in FIG. 59. (Note that otherpulse-width-to-period ratios of 3/(2·n), 5/(2·n), etc., will haveamplitudes that are equal to but not larger than this one.)

[0637] This is one approach to determining the desiredpulse-width-to-period ratio. Those skilled in the relevant art(s) willunderstand that other techniques may also be used to select apulse-width-to-period ratio.

[0638] 7.6 Design of the Pulse Shaping Circuit.

[0639] Once the determination has been made as to the desired frequencyof the oscillating signal 5704, 5738, 5744 and of the pulse width, thepulse shaping circuit 5722 can be designed. Looking back to sections4-4.3.4 it can be seen that the pulse shaping circuit 5722 can not onlyproduce a pulse of a desired pulse width, but it can also cause thefrequency of the string of pulses 5706 to be higher than the frequencyof the oscillating signal 5704, 5738, 5744. Recall that thepulse-width-to-period ratio applies to the pulse-width-to-period ratioof the harmonically rich signal 5708 and not to thepulse-width-to-period ratio of the oscillating signal 5704, 5738, 5744,and that the frequency and pulse width of the harmonically rich signal5708 mirrors the frequency and pulse width of the string of pulses 5706.Thus, if in the selection of the VCO 5720 or LO 5734 it was desired tochoose an oscillator that is lower than that required for the selectedharmonic, the pulse shaping circuit 5733 can be used to increase thefrequency. Going back to the previous example, the frequency of theoscillating signal 5704, 5738, 5744 could be 50.5556 MHz rather than101.1111 MHz if the pulse shaping circuit 5722 was designed such asdiscussed in sections 4.2.2-4.2.2.2 (shown in FIGS. 40A-40D) not only toshape the pulse, but also to double the frequency. While that discussionwas specifically for a square wave input, those skilled in the relevantart(s) will understand that similar techniques will apply tonon-rectangular waveforms (e.g., a sinusoidal wave). This use of thepulse shaping circuit to double the frequency has a possible advantagein that it allows the design and selection of an oscillator (VCO 5720 ofLO 5734) with a lower frequency, if that is a consideration.

[0640] It should also be understood that the pulse shaping circuit 5722is not always required. If the design or selection of the VCO 5720 or LO5734 was such that the oscillating signal 5704, 5738, 5744 was asubstantially rectangular wave, and that substantially rectangular wavehad a pulse-width-to-period ratio that was adequate, the pulse shapingcircuit 5722 could be eliminated.

[0641] 7.7 Selection of the Switch.

[0642] The selection of a switch 5724 can now be made. The switch 5724is shown in the examples of FIGS. 57A, 57B, and 57C as a GaAsFET.However, it may be any switching device of any technology that can openand close “crisply” enough to accommodate the frequency and pulse widthof the string of pulses 5706.

[0643] 7.8 Design of the Filter.

[0644] The design of the filter 5726 is determined by the frequency andfrequency range of the desired transmission signal 5714. As discussedabove in sections 3.3.9-3.3.9.2, the term “Q” is used to describe theratio of the center frequency of the output of the filter to thebandwidth of the “3 dB down” point. The trade offs that were made in theselection of the subharmonic to be used is a factor in designing thefilter. That is, if, as an excursion to the example given above, thefrequency of the desired transmission signal were again 910 MHz, but thedesired subharmonic were the 50^(th) subharmonic, then the frequency ofthat 50^(th) subharmonic would be 18.2000 MHz. This means that thefrequencies seen by the filter will be 18.200 MHz apart. Thus, the “Q”will need to be high enough to avoid allowing information from theadjacent frequencies being passed through. The other consideration forthe “Q” of the filter is that it must not be so tight that it does notpermit the usage of the entire range of desired frequencies.

[0645] 7.9 Selection of an Amplifier.

[0646] An amplifier module 5728 will be needed if the signal is notlarge enough to be transmitted or if it is needed for some downstreamapplication. This can occur because the amplitude of the resultantharmonic is too small. It may also occur if the filter 5726 hasattenuated the signal.

[0647] 7.10 Design of the Transmission Module.

[0648] A transmission module 5730, which is optional, ensures that theoutput of the filter 5726 and the amplifier module 5728 is able to betransmitted. In the implementation wherein the transmitter is used tobroadcast EM signals over the air, the transmission module matches theimpedance of the output of the amplifier module 0.5728 and the input ofan antenna 5732. This techniques is well known to those skilled in therelevant art(s). If the signal is to be transmitted over apoint-to-point line such as a telephone line (or a fiber optic cable)the transmission module 5730 may be a line driver (or anelectrical-to-optical converter for fiber optic implementation).

What is claimed is:
 1. A method for up-converting an electromagneticsignal, the electromagnetic signal having a first frequency, comprising:(1) gating a bias signal at a rate proportional to the first frequencyof the electromagnetic signal to generate a harmonically rich signalhaving a plurality of harmonics; and (2) selecting at least one of saidplurality of harmonics as a desired signal having at least a secondfrequency.
 2. The method of claim 1, further comprising: (3) shaping theelectromagnetic signal, resulting in a shaped signal, said shaped signalbeing a substantially rectangular waveform having a third frequency,said third frequency being proportional to the first frequency, saidsubstantially rectangular waveform further having a period that is aninverse of said third frequency, a pulse width, and a pulse ratio, saidpulse ratio being a ratio of said pulse width to said period; andwherein said bias signal is gated in step (1) at a rate proportional tosaid third frequency.
 3. The method of claim 2, wherein said pulse ratiois substantially equal to or less than 0.5.
 4. The method of claim 1,wherein the electromagnetic signal is modulated.
 5. The method of claim1, wherein said bias signal is related to an information signal.
 6. Themethod of claim 1, wherein said second frequency is higher than thefirst frequency.